<PAGE>   1
                                                                 EXHIBIT 10.3

                       TRANSPORTADORA DE GAS DEL SUR S.A.


                                      AND


                        CITICORP TRUSTEE COMPANY LIMITED





       _________________________________________________________________

                        FURTHER SUPPLEMENTAL TRUST DEED

                                  RELATING TO

                                U.S.$350,000,000

                        EURO MEDIUM-TERM NOTE PROGRAMME
          ____________________________________________________________





                                October 23, 1996





                                Clifford Chance
                                    New York
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THIS FURTHER SUPPLEMENTAL TRUST DEED is made on October 23, 1996

BETWEEN

(1)      TRANSPORTADORA DE GAS DEL SUR S.A. (the "ISSUER"); and

(2)      CITICORP TRUSTEE COMPANY LIMITED (the "TRUSTEE").

WHEREAS

(A)      The parties to this Deed have entered into a trust deed dated December
         14, 1993 and a Supplemental Trust Deed dated July 25, 1995 (together
         the "TRUST DEED") relating to the issuance of Euro Medium-Term Notes.

(B)      This Deed is supplemental to and amends the Trust Deed.


IT IS AGREED as follows:

1.       INTERPRETATION

In this Deed, unless otherwise specified herein, terms and expressions defined
in the Trust Deed have the same meaning.

2.       AMENDMENTS

The Trust Deed is amended as follows:

(a)      by inserting the words "and Resolution No. 11,484 dated October 17,
         1996 of the CNV" in the definition of "Notes" after the letters "CNV"
         in the parenthetical phrase in the fifth and sixth lines;

(b)      in Clause 2.1, by replacing the amount "U.S.$350,000,000" with the
         amount "U.S.$500,000,000" in the penultimate paragraph; and

(c)      by replacing in its entirety, in relation to Notes issued on or after
         the date hereof, the Seventh Schedule to the Trust Deed with the
         Seventh Schedule set out in the Schedule to this Deed.

3.       LAW AND JURISDICTION

3.01     GOVERNING LAW:  This Deed is governed by, and shall be construed in
         accordance with, English law.
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3.02     JURISDICTION:  Clauses 17.2, 17.3 and 17.4 of the Trust Deed apply to
         this Deed, mutatis mutandis, as if set out in full herein.

4.       COUNTERPARTS

This Agreement may be signed in counterparts, each of which when so executed
shall be deemed to be an original and all of which when taken together shall
constitute a single agreement.

IN WITNESS WHEREOF this Further Supplemental Trust Deed has been executed as a
deed by the Issuer and the Trustee and is intended to be and is hereby
delivered on the date first above written.
<PAGE>   4
                              THE SEVENTH SCHEDULE

                       TERMS AND CONDITIONS OF THE NOTES

The following is the English text of the terms and conditions, which, subject
to completion and amendment and as supplemented or varied in accordance with
the provisions of the relevant Pricing Supplement, will be endorsed on the
Notes in definitive form (if any) issued in exchange for the Temporary Global
Note(s), Permanent Global Note(s) and Registered Global Note(s) representing
each Series, and attached to any such Note(s) in global form, details of the
relevant Series being shown on the face of the relevant Notes and in the
relevant Pricing Supplement:

The establishment of the programme was authorized by a resolution of the
shareholders of the Issuer passed on August 27, 1993, as amended by a
resolution of such shareholders passed on March 6, 1996 and by resolutions of
the board of directors of the Issuer passed on August 27, 1993, November 4,
1993, November 10, 1993, November 30, 1993 and amended by resolutions of the
Board of Directors, passed on July 4, 1995 and September 12, 1996.  The Notes
are constituted under a trust deed (as amended, supplemented or replaced from
time to time, the "Trust Deed") dated December 14, 1993, between the Issuer and
Citicorp Trustee Company Limited (the "Trustee", which expression shall include
all persons for the time being the trustee or trustees under the Trust Deed) as
trustee for the holders of the Notes (the "Noteholders").  These Conditions
include summaries of, and are subject to, the detailed provisions of the Trust
Deed, which includes the form of the Notes and the coupons relating to them
(the "Coupon").  Copies of the Trust Deed, and of the agency agreement (as
amended, supplemented or replaced from time to time, the "Agency Agreement")
dated December 14, 1993, relating to the Notes, between the Issuer, the
Trustee, the paying agents named in it, Citibank N.A. acting through its Buenos
Aires office in its capacity as paying agent and registrar (the "Paying Agent
in Buenos Aires" and "Registrar", which expression shall include any successor
to Citibank, N.A. in its capacity as such) and the transfer agents named in it,
are available for inspection during usual business hours at the principal
office of the Trustee (presently at 336 Strand, London WC2R 1HB) and of the
Trustee's representative in Argentina and at the specified offices of the
paying agents (the "Paying Agents", which expression shall include the
Principal Paying Agent (as defined in the Agency Agreement and designated in
the relevant Pricing Supplement)), the Registrar and the transfer agents,
including Citibank N.A. acting through its specified office in New York City as
transfer agent (the "New York Transfer Agent") for the time being (the
"Transfer Agents").  The Trustee has appointed Citibank N.A. presently at
Bartolome Mitre 502, 1036-Buenos Aires as its agent in Buenos Aires to receive
notices on its behalf in Argentina from Noteholders and to act on the Trustee's
behalf as necessary The Noteholders and the holders of the Coupons (whether or
not attached to the relevant Notes) (the "Couponholders") are entitled to the
benefit of, are bound by, and are deemed to have notice of, all the provisions
of the Trust Deed and are deemed to have notice of those provisions applicable
to them of the Agency Agreement.

The Notes are issued in series (each a "Series" made up of one or more tranches
(each a "Tranche")), and each Series will be the subject of a pricing
supplement specifying the relevant issue details in relation to each Series and
supplementing or varying the terms hereof (each a "Pricing Supplement") a copy
of which will be available at the specified office of each of the Trustee and
the Issue Agent or, as the case may be, the New York Transfer Agent, and a copy
of which will, in the case of a Series in relation to which application has
been made for admission to the Official List of the Luxembourg Stock Exchange
(the
<PAGE>   5
"Luxembourg Stock Exchange"), be lodged with the Luxembourg Stock Exchange and
will be available without charge at the specified office of the Paying Agent in
Luxembourg.

For the purposes of these Conditions, references to "Notes" shall, as the
context may require, be deemed to be to the Temporary Global Notes, Permanent
Global Notes, Definitive Bearer Notes, Registered Global Notes or, as the case
may be, Definitive Registered Notes.  References to "Noteholders" shall include
Couponholders, as the context may require.

1.       FORM AND DENOMINATION

(a)      FORM:  The Notes are issued in bearer form or in registered form, as
specified in the relevant Pricing Supplement which is to be construed as
included herein, and issued in respect of each issue of Notes specifying the
relevant issue details in relation to each issue of Notes and supplementing or
varying the terms thereof.

(b)      EXCHANGE OF NOTES IN GLOBAL FORM:

         (i)     Notes issued in bearer form ("Bearer Notes") will be
                 represented upon issue by a temporary global note (a
                 "Temporary Global Note") in substantially the form (subject to
                 amendment and completion) scheduled to the Trust Deed.  On or
                 after the date (the "Exchange Date") which is 40 days after
                 the completion of the distribution of the Notes of the
                 relevant Tranche and provided certification as to the
                 beneficial ownership thereof as required by U.S. Treasury
                 regulations (substantially in the form set out in the
                 Temporary Global Note) has been received, interests in the
                 Temporary Global Note may be exchanged for:

                 (aa)     interests in a permanent global note in bearer form
                          (a "Permanent Global Note") representing the Notes of
                          that Series and in substantially the form (subject to
                          amendment/and completion) scheduled to the Trust
                          Deed; or

                 (bb)     if so specified in the relevant Pricing Supplement,
                          definitive Notes in bearer form ("Definitive Bearer
                          Notes") in substantially the forms (subject to
                          amendment and completion) scheduled to the Trust
                          Deed; or

                 (cc)     if so specified in the relevant Pricing Supplement,
                          Notes in registered form ("Registered Notes") in the
                          form either of definitive Notes in registered form
                          ("Definitive Registered Notes") or of interests in a
                          registered global note (a "Registered Global Note"),
                          in each case in substantially the forms (subject to
                          amendment and completion) scheduled to the Trust
                          Deed,

                 which interests or Notes, as the case may be, may be obtained
                 at any time, subject to the provisions of the relevant
                 Temporary Global Note.

        (ii)     Interests in a Permanent Global Note will, unless the contrary
                 is specified in the relevant Pricing Supplement, be
                 exchangeable in whole or in part, at the option of the Holders
                 of
<PAGE>   6
                 interests in such Permanent Global Note, for other Notes,
                 including Definitive Bearer Notes or interests in a Registered
                 Global Note.

       (iii)     Notes issued in either only registered form or in both
                 registered and bearer form will be represented on issue by
                 Notes in the following form:

                 (aa)     Notes initially sold in an offshore transaction in
                          reliance on Regulation S under the United States
                          Securities Act of 1933, as amended (the "Securities
                          Act") may be represented by an unrestricted
                          Registered Global Note ("an Unrestricted Registered
                          Global Note") or a restricted Registered Global Note
                          (a "Restricted Registered Global Note") which would
                          be deposited with the New York Transfer Agent as
                          custodian for The Depository Trust Company ("DTC")
                          and registered in the name of a nominee of DTC or a
                          Temporary Global Note.

                 (bb)     Notes initially sold within the United States in
                          reliance on Rule 144A under the Securities Act may be
                          represented by a Restricted Registered Global Note
                          which would be deposited with the New York Transfer
                          Agent as custodian for DTC and registered in the name
                          of a nominee of DTC.

                          An interest in a Registered Global Note may be
                          exchanged for a Definitive Registered Note and, if so
                          specified in the relevant Pricing Supplement, an
                          interest in another Registered Global Note.  A
                          Definitive Registered Note may be exchanged for an
                          interest in a Registered Global Note or for another
                          Definitive Registered Note under certain
                          circumstances described in the Trust Deed.

(c)      SURRENDER OF GLOBAL NOTES IN EXCHANGE FOR DEFINITIVE NOTES:  In order
to exchange interests in a global Note for definitive Notes, a Holder must, not
less than 45 days before the date on which delivery of definitive Notes is
required, surrender or, as the case may be, present the relevant Temporary
Global Note or Permanent Global Note at the specified office of the Principal
Paying Agent or, as the case may be, present the relevant Registered Global
Note at the specified office of the New York Transfer Agent, together, in each
case, with a request in writing specifying the principal amount of such
Temporary Global Note or Permanent Global Note or, as the case may be,
Registered Global Note, to be exchanged.  Any such definitive Notes shall be
issued within 45 days of the delivery of such notice to such office.

(d)      SURRENDER OF DEFINITIVE NOTES IN EXCHANGE FOR OTHER DEFINITIVE NOTES:
Definitive Bearer Notes will, unless the contrary is specified in the relevant
Pricing Supplement, be exchangeable for Definitive Registered Notes.  In order
to exercise such option, the Holder must, not less than 45 days before the date
on which delivery of the Definitive Registered Note is required, surrender the
Definitive Bearer Note at the specified office of any Paying Agent located
outside the United States and its possessions, together with a request in
writing specifying the name in which the Definitive Registered Note is to be
issued.  Definitive Registered Notes will, unless the contrary is specified in
the relevant Pricing Supplement, be exchangeable in whole or in part for
another Definitive Registered Note.  In order to exercise such option, the
Holder must, not less than 45 days before the date on which delivery of the
Definitive Registered Note is required, surrender the Definitive Registered
Note at the specified office of a Transfer Agent, together with a request in
writing specifying the name in which the new Definitive Registered Note is to
be issued.
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(e)      COUPONS:  Interest-bearing Definitive Bearer Notes will have attached
thereto at the time of their initial delivery Coupons, presentation of which
will be a prerequisite to the payment of interest in certain circumstances
specified below.

(f)      EXCHANGE OF REGISTERED NOTES:  Registered Notes will not be
exchangeable for Bearer Notes.

(g)      DENOMINATION OF BEARER NOTES:  Bearer Notes will be issued in
denominations of U.S.$10,000 and U.S.$100,000 or such other denominations
specified in the relevant Pricing Supplement.  Bearer Notes of one denomination
will not be exchangeable after their initial delivery for Bearer Notes of any
other denomination.

(h)      DENOMINATION OF REGISTERED NOTES:  Registered Notes will be in the
denomination of U.S.$250,000 or higher multiples of U.S.$10,000 or, otherwise
as specified in the relevant Pricing Supplement.

(i)      CURRENCY OF NOTES:  Notes may be denominated in United States dollars
or any other currency except the European Currency Unit ("Ecu") subject to
compliance with all applicable Argentine and other legal or regulatory
requirements.

(j)      THE DEPOSITORY TRUST COMPANY:  Registered Notes denominated in United
States dollars will, if so specified in the relevant Pricing Supplement, be the
subject of an application by the Issuer to The Depository Trust Company ("DTC")
for the acceptance of such Registered Notes into DTC's book-entry settlement
system.  If such application is accepted, one or more Registered Global Notes
(each a "DTC Note") in denominations equivalent in aggregate to the aggregate
principal amount of relevant Registered Notes which are to be held in such
system will be issued to DTC and registered in the name of Cede & Co., or such
other person as may be nominated by DTC for the purpose, as nominee for DTC.
Thereafter, such registered nominee will be the holder of record and entitled
to rights in respect of each DTC Note.  Accordingly, each person having a
beneficial interest in a DTC Note must rely on the procedures of the
institutions having accounts with DTC to exercise any rights of such person.
So long as Registered Notes are traded through DTC's book-entry settlement
system, ownership of beneficial interest in the relevant DTC Note will (unless
otherwise required by applicable law) be shown on, and transfers of such
beneficial interest may be effected only through, records maintained by (i) DTC
or its registered nominee (as to DTC Participant-interests) or (ii)
institutions having accounts with DTC (including, without limitation, Morgan
Guaranty Trust Company of New York, Brussels office, as operator of Euroclear
System ("Euroclear") and Cedel Bank, sociJtJ anonyme ("Cedel")).

(k)      SPANISH TEXT:  The Notes contain a Spanish translation of the English
text.

2.       TITLE

(a)      TITLE TO BEARER NOTES:  Title to Bearer Notes passes by delivery.
References herein to "Holders" of Bearer Notes or of Coupons signify the
bearers of such Bearer Notes or such Coupons.
<PAGE>   8
(b)      TITLE TO REGISTERED NOTES:  Title to Registered Notes passes by
registration in the register which is kept by the Registrar.  References herein
to the "Holders" of Registered Notes signify the persons in whose names such
Notes are so registered.

(c)      OWNERSHIP:  The Holder of any Note or Coupon will (except as otherwise
required by law) be treated as its absolute owner for all purposes (whether or
not it is overdue and regardless of any notice of ownership, trust or any
interest in it, any writing on it, or its theft or loss) and no person shall be
liable for so treating the Holder.

(d)      TRANSFER OF REGISTERED NOTES:  A Registered Note may, upon the terms
and subject to the conditions set forth in the Agency Agreement, be transferred
in whole or in part only (provided that such part is, or is an integral
multiple of, the minimum denomination specified in the relevant Pricing
Supplement) upon the surrender of the Registered Note to be transferred,
together with such other documents as may be required, at the specified office
of a Transfer Agent.  A new Registered Note will be issued to the transferee
and, in the case of a transfer of part only of a Registered Note, a new
Registered Note in respect of the balance not transferred will be issued to the
transferor.

(e)      DELIVERY OF NEW REGISTERED NOTES:  Each new Registered Note to be
issued upon the transfer of Registered Notes will, upon the effective receipt
of such other documents required by a Transfer Agent at its specified office,
be available for delivery at the specified office of such Transfer Agent.  For
these purposes, documentation received by a Transfer Agent during the period of
15 Business Days ending on the due date for any payment on the relevant
Registered Notes shall be deemed not to be effectively received by such
Transfer Agent until the day following the due date for such payment.

(f)      CHARGES ON TRANSFER:  The issue of new Registered Notes on transfer
will be effected without charge by or on behalf of the Issuer, the Registrar or
the Transfer Agents, but upon payment by the applicant of (or the giving by the
applicant of such indemnity as the Registrar or the Transfer Agents may require
in respect of) any tax or other governmental charges which may be imposed in
relation thereto.

(g)      PRIVATE PLACEMENT LEGEND:  The Issuer covenants and agrees that it
will not acquire any beneficial interest, and will cause its "affiliates" (as
defined in paragraph (a)(1) of Rule 144 under the Securities Act) not to
acquire any beneficial interest, in any Registered Note bearing a restrictive
legend unless it notifies the New York Transfer Agent of such acquisition.  The
Registrar, the New York Transfer Agent and all Holders of Notes shall be
entitled to rely without further investigation on any such notification (or
lack thereof).

(h)      RULE 144A(d)(4):  For so long as any of the Registered Notes bearing a
restrictive legend remain outstanding and are "restricted securities" within
the meaning of Rule 144(a)(3) under the Securities Act, the Issuer covenants
and agrees that it shall, during any period in which it is not subject to
Section 13 or 15(d) under the United States Securities Exchange Act of 1934 nor
exempt from reporting pursuant to Rule 12g3-2(b) under such Act, make available
to any Holder of such Notes in connection with any sale thereof and any
prospective purchaser of such Notes from such Holder, in each case upon
request, the information specified in, and meeting the requirements of, Rule
144A(d)(4) under the Securities Act.
<PAGE>   9
3.       STATUS

The Notes constitute "Obligaciones Negociables" under Law No. 23,576 of
Argentina, as amended by Law No. 23,962 (the "Negotiable Obligations Law"), and
are entitled to the benefits set forth therein and are subject to the
procedural requirements thereof.  In particular, pursuant to Article 29 of the
above Law, in the event of a default by the Issuer in the payment of principal,
interest and any other amounts due under any Note, the holder of such Note will
be entitled to take summary judicial proceedings ("accion ejecutiva") to
recover payment of any such amount.  Unless otherwise specified in the
applicable Pricing Supplement, the Notes and Coupons constitute direct,
unconditional and unsecured obligations of the Issuer and shall at all times
rank pari passu and without any preference among themselves.  The payment
obligations of the Issuer under the Notes and Coupons shall, other than in the
case of obligations preferred by mandatory provisions of law and subject to
Condition 4, at all times rank at least equally with all its other present and
future unsecured and unsubordinated obligations.

4.       NEGATIVE PLEDGE AND CERTAIN OTHER COVENANTS

(a)      NEGATIVE PLEDGE:

         (i)     So long as any Note remains outstanding, the Issuer will not,
                 and the Issuer will procure that none of its Subsidiaries
                 will, create or permit to subsist any mortgage, charge,
                 pledge, lien or other form of encumbrance or security interest
                 ("Lien") upon the whole or any part of its or, as the case may
                 be, any such Subsidiary's undertaking, assets or revenues
                 present or future to secure (a) any Indebtedness or (b) any
                 guarantee of or indemnity in respect of any Indebtedness
                 unless, at the same time or prior thereto, the Issuer's
                 obligations under the Notes and the Trust Deed (x) are secured
                 equally and rateably therewith or benefit from a guarantee or
                 indemnity in substantially identical terms thereto, as the
                 case may be, in each case to the satisfaction of the Trustee,
                 or (y) have the benefit of such other security, guarantee,
                 indemnity or other arrangement as shall be approved by an
                 Extraordinary Resolution of the Noteholders.

        (ii)     The following exceptions apply to the Issuer's obligations set
                 out in paragraph (i) above:

                 (aa)     Liens existing on December 14, 1993;

                 (bb)     any Lien created on any fixed asset securing
                          Indebtedness incurred or assumed solely for the
                          purpose of financing all or any part of the cost of
                          acquiring such fixed asset, which Lien attaches to
                          such fixed asset concurrently with or within 90 days
                          after the acquisition thereof;

                 (cc)     any Lien created on any asset securing Indebtedness
                          incurred in relation to the construction or
                          development, as the case may be, in whole or in part,
                          of (a) assets used in, processing and/or distribution
                          and/or transportation of gas and (b) gas processing
                          plants and/or gas distribution facilities and/or gas
                          transportation facilities, where in either case such
                          Lien is created over such asset;
<PAGE>   10
                 (dd)     any Lien created on any asset securing an extension,
                          renewal or refinancing of Indebtedness secured in
                          accordance with (aa), (bb) or (cc) of this paragraph
                          (ii) provided that (a) the Lien is created over the
                          original asset secured and (b) the principal amount
                          of Indebtedness secured by the Lien prior to such
                          extension, renewal or refinancing is not increased;
                          and

                 (ee)     all Liens created on any asset securing Indebtedness,
                          other than Liens described in (aa), (bb), (cc) or
                          (dd) of this paragraph (ii) the aggregate amount of
                          which does not exceed U.S.$10,000,000.

       (iii)     In this Condition:

                 "Indebtedness" means any obligation present or future (actual
                 or contingent) for the payment or repayment of money which has
                 been borrowed or raised, including obligations for the payment
                 of the deferred purchase price of assets and obligations which
                 may arise under a guarantee or indemnity or other similar
                 obligation.

                 "Subsidiary" means (a) any corporation or other entity of
                 which the Issuer either (i) is a shareholder and controls the
                 composition of its Board of Directors, or (ii) holds 50% or
                 more in nominal value or par value of its equity share
                 capital, or (b) any corporation or other entity which is
                 itself a subsidiary of any corporation or other entity which
                 is a Subsidiary of the Issuer.

(b)      FINANCIAL COVENANT:  At each Interim Balance Sheet Date or Annual
Balance Sheet Date, as the case may be, and in accordance with Argentine
generally accepted accounting principles, Defined Debt divided by the aggregate
of Defined Debt and Common Stockholders' Equity, expressed as a percentage,
will not exceed 60% as reflected in the respective Interim Balance Sheet or, as
the case may be, Annual Balance Sheet as at such date.

In this Condition:

         "Annual Balance Sheet" of a company means the balance sheet of such
         company as of the end of the Issuer's fiscal year;

         "Annual Balance Sheet Date" means the date on which the Issuer's
         fiscal year ends;

         "Annual Period" means the Issuer's fiscal year;

         "Common Stockholder's Equity" means the sum of capital stock, retained
         earnings and reserves of the Issuer;

         "Defined Debt" means the aggregate of the total indebtedness for or in
         respect of money borrowed or raised by the Issuer as reflected in the
         latest unconsolidated Interim Balance Sheet of the Issuer or, as the
         case may be, unconsolidated Annual Balance Sheet of the Issuer, and
         the
<PAGE>   11
         proportion of the total indebtedness for or in respect of money
         borrowed or raised by any Subsidiary as disclosed in such Subsidiary's
         consolidated Interim Balance Sheet or, as the case may be, Annual
         Balance Sheet corresponding on a pro rata basis to the Issuer's
         ownership in each such Subsidiary but excluding any indebtedness as
         aforesaid between the Issuer and such Subsidiary.

         For the purpose of this definition "Subsidiary" shall have the meaning
         set out in Condition 4(a).

         "Interim Balance Sheet" of a company means the balance sheet of such
         company as of the end of each six monthly period in any Annual Period;
         and

         "Interim Balance Sheet Date" means the date on which each of the
         Issuer's six monthly periods in any Annual Period ends.

5.       INTEREST

(a)      PRICING SUPPLEMENT:  Notes may be interest-bearing or non-interest
bearing, as specified in the relevant Pricing Supplement.  The Pricing
Supplement in relation to each Series of interest-bearing Notes shall specify
which one (and one only) of Condition 5(b) or 5(c) shall be applicable, save to
the extent that Condition 5(b) or 5(c) are inconsistent with the relevant
Pricing Supplement, in which case the relevant Pricing Supplement will prevail.

(b)      INTEREST-FIXED RATE:  Notes in relation to which this Condition 5(b)
is specified in the relevant Pricing Supplement as being applicable shall bear
interest from their date of issue at the rate specified in the relevant Pricing
Supplement.  Such interest will be payable in arrears on such dates as are
specified in the relevant Pricing Supplement and on the date of final maturity
thereof.  Such interest will be calculated on the basis of a 360-day year
consisting of 12 months of 30 days each (or such other basis set forth in the
Pricing Supplement) and, in the case of an incomplete month, the actual number
of days elapsed or on such other basis as may be specified in the relevant
Pricing Supplement.

(c)      INTEREST-OTHER RATES:  Notes in relation to which this Condition 5(c)
is specified in the relevant Pricing Supplement as being applicable shall bear
interest at the rates per annum or payable in the amounts and in the manner
determined in accordance with the relevant Pricing Supplement.

(d)      INTEREST-SUPPLEMENTAL PROVISION:  The determination by the Trustee,
the Principal Paying Agent or such other agent as is specified in the relevant
Pricing Supplement of all rates of interest and amounts of interest for the
purposes of this Condition 5 shall, in the absence of manifest error, be final
and binding on all parties.

6.       REDEMPTION AND PURCHASE

(a)      REDEMPTION AT MATURITY:  Unless previously redeemed or purchased and
cancelled, Notes shall be redeemed at their principal amount (or such other
redemption amount as may be specified in the relevant Pricing Supplement) on
the date or dates specified in the relevant Pricing Supplement.
<PAGE>   12
(b)      EARLY REDEMPTION FOR TAXATION REASONS:  If, in relation to any Series
of Notes (i) as a result of any change in, or amendment to, the laws or
regulations of Argentina or of any political subdivision or authority or agency
thereof or any change in the application or official interpretation of any such
laws or regulations, which change or amendment becomes effective on or after
the date of issue of such Notes or any earlier date specified in the relevant
Pricing Supplement on the occasion of the next payment due in respect of such
Notes the Issuer would be required to pay Additional Amounts (as defined in
Condition 8); and (ii) such obligation cannot be avoided by the Issuer taking
reasonable measures available to it, the Issuer may, at its option and having
given no less than 30 nor more than 60 days' notice to the Holders in
accordance with Condition 15 (which notice shall be irrevocable) redeem all
(but not some only) of the outstanding Notes comprising the relevant Series at
their principal amount (or at such other early redemption amount as may be
specified in the relevant Pricing Supplement), together with accrued interest
(if any) thereon provided, however, that no such notice of redemption may be
given earlier than 90 days prior to the earliest date on which the Issuer would
be obliged to pay such Additional Amounts were a payment in respect of the
Notes then due.  Prior to the publication of any notice of redemption pursuant
to this paragraph, the Issuer shall deliver to the Trustee (x) an opinion of
independent counsel of recognized standing addressed to the Trustee to the
effect that the Issuer has or will become obliged to pay the Additional Amounts
referred to in (i) above, and (y) a certificate signed by two Directors of the
Issuer stating that the obligation referred to in (ii) above cannot be avoided
by the Issuer taking reasonable measures available to it and the Trustee shall
be entitled to accept such opinion and certificate, respectively, as sufficient
evidence of the satisfaction of the respective conditions precedent set out in
(i) and (ii) above in which event such opinion and certificate, respectively,
shall be conclusive and binding on the Noteholders and the Couponholders.

(c)      OPTIONAL EARLY REDEMPTION (CALL):  If this Condition 6(c) is specified
in the relevant Pricing Supplement as being applicable, then the Issuer may,
upon the expiry of the appropriate notice and subject to such conditions as may
be specified in the relevant Pricing Supplement, redeem all (but not, unless
and to the extent that the relevant Pricing Supplement specifies otherwise,
some only), of the Notes of the relevant Series at their principal amount (or
such other redemption amount as may be specified in the relevant Pricing
Supplement), together with accrued interest (if any) thereon.

(d)      CALL NOTICE:  The appropriate notice referred to in Condition 6(c) is
a notice given by the Issuer to the Trustee, and the Principal Paying Agent,
the New York Transfer Agent (in the case of the Registered Notes) and the
Holders of the Notes of the Relevant Series, which notice shall be signed by
two Directors of the Issuer and shall specify:

         (i)     the Series of Notes subject to redemption;

        (ii)     whether such Series is to be redeemed in whole or in part only
                 and the aggregate principal amount of the Notes of the
                 relevant Series which are to be redeemed; and

       (iii)     the due date for such redemption, which shall be not less than
                 30 days (or such lesser period as may be specified in the
                 relevant Pricing Supplement) after the date on which such
                 notice is validly given.
<PAGE>   13
Any such notice shall be irrevocable, and the delivery thereof shall oblige the
Issuer to make the redemption therein specified.

(e)      PARTIAL REDEMPTION:  If only some of the Notes of a Series are to be
redeemed in part only on any date in accordance with Condition 6(c):

         (i)     in the case of the Bearer Notes, the Notes to be redeemed
                 shall be drawn by lot in such European city as the Trustee may
                 specify, or identified in such other manner or in such other
                 place as the Trustee may approve and deem appropriate and
                 fair, subject always to compliance with all applicable laws
                 and the requirements of any stock exchange on which the
                 relevant Notes may be listed; and

        (ii)     in the case of Registered Notes, the Notes shall be redeemed
                 pro rata to their principal amounts or by lot or by a method
                 the Trustee considers fair and appropriate, subject always as
                 aforesaid.

(f)      OPTIONAL EARLY REDEMPTION (PUT):  If this Condition 6(f) is specified
in the relevant Pricing Supplement as being applicable, then the Issuer shall,
upon the exercise of the relevant option by the Holder of any Note of the
relevant Series, redeem such Note on the date or the next of the dates
specified in the relevant Pricing Supplement at its principal amount (or such
other redemption amount as may be specified in the relevant Pricing
Supplement), together with accrued interest (if any) thereon.  In order to
exercise such option the Holder must, not less than 45 days before the date so
specified (or such other period as may be specified in the relevant Pricing
Supplement), deposit the relevant Note (together, in the case of an
interest-bearing Definitive Bearer Note, with any unmatured Coupons
appertaining thereto) with, in the case of a Bearer Note, any Paying Agent
outside the United States or its possessions or, in the case of a Registered
Note, any Transfer Agent together with a duly completed letter of transmittal
in the form which is available from the specified office of any of the Paying
Agents or, as the case may be, any Transfer Agent.

(g)      PURCHASE:  The Issuer or any of its Subsidiaries may at any time
purchase Notes in the open market or otherwise at any price (provided that, in
the case of interest-bearing Definitive Bearer Notes, they are purchased
together with all unmatured Coupons relating to them) in accordance with
applicable legal and regulatory requirements.  Any purchase by tender shall be
made available to all Noteholders alike.  The Notes so purchased, while held by
or on behalf of the Issuer or such Subsidiary or Affiliate (as defined in the
Trust Deed), shall not entitle the holder to vote at any meetings of the
Noteholders and shall not be deemed to be outstanding for the purposes of
calculating quorums at meetings of the Noteholders or for the purposes of
Condition 12(a).

(h)      CANCELLATION:  All Notes bearing a restrictive legend so redeemed or
purchased will be cancelled and may not be re-issued or resold unless otherwise
specified in the Pricing Supplement.
<PAGE>   14
7.       PAYMENTS

(a)      PAYMENTS-GENERAL PROVISIONS:  Payments of amounts due (whether in
respect of principal, interest or otherwise) in respect of any Note will be
made by cheque or transfer in the currency of such Note drawn on a bank in the
Relevant Financial Center in accordance with this Condition.  Save as otherwise
specified herein, this Condition 7(a) is applicable to the Notes whether in
bearer or registered form.

(b)      PAYMENTS-BEARER NOTES:

         (i)     This Condition 7(b) is applicable in relation to Notes
                 specified in the relevant Pricing Supplement as being in
                 bearer form;

        (ii)     Payment of amounts (including accrued interest) due on the
                 redemption of Bearer Notes will be made against presentation
                 and, save in the case of a partial redemption by reason of
                 insufficiency of funds, surrender of the relevant Bearer Notes
                 at the specified office outside the United States or its
                 possessions of any of the Paying Agents, by cheque or by
                 transfer to a designated account located outside the United
                 States or its possessions;

       (iii)     Payment of amounts due in respect of interest on Bearer Notes
                 will be made:

                 (aa)     in the case of a Temporary Global Note, only in
                          circumstances where an exchange for an interest in a
                          Note in Global or definitive form has been improperly
                          withheld or refused;

                 (bb)     in the case of a Permanent Global Note, against
                          presentation and endorsement of the relevant
                          Permanent Global Note at the specified office outside
                          the United States or its possessions of any of the
                          Paying Agents, through Euroclear and Cedel;

                 (cc)     in the case of Bearer Notes without Coupons attached
                          thereto at the time of their initial delivery,
                          against presentation and endorsement of the relevant
                          Bearer Notes at the specified office outside the
                          United States or its possessions of any of the Paying
                          Agents, by cheque or by transfer to a designated
                          account located outside the United States or its
                          possessions;

                 (dd)     in the case of Bearer Notes with Coupons attached
                          thereto at the time of their initial delivery,
                          against presentation of the relevant Coupons at the
                          specified office outside the United States or its
                          possessions of any of the Paying Agents, by cheque or
                          by transfer to a designated account located outside
                          the United States or its possessions.

        (iv)     If the due date for payment of any amount due (whether in
                 respect of principal, interest or otherwise) in respect of any
                 Bearer Notes is not a Business Day, then the Holder thereof
<PAGE>   15
                 will not be entitled to payment thereof until the next
                 following such Business Day and no further payment shall be
                 due in respect of such delay save in the event that there is a
                 subsequent failure to pay in accordance with these Conditions.

         (v)     Payments of interest and principal in respect of Bearer Notes
                 may only be made at the specified offices of Paying Agents
                 outside the United States of America, except that payments
                 denominated in U.S. dollars may be made at the specified
                 office of a Paying Agent in New York City if (i) the Issuer
                 shall have appointed Paying Agents with specified offices
                 outside the United States of America with the reasonable
                 expectation that such Paying Agents would be able to make
                 payment at such offices of the full amount of the interest and
                 principal of the Notes in U.S. dollars when due, (ii) payment
                 of the full amount of such interest and principal in U.S.
                 dollars at all specified offices of the Paying Agents outside
                 the United States of America is illegal or effectively
                 precluded by exchange controls or other similar restrictions,
                 and (iii) the relevant payment is permitted by applicable U.S.
                 law.

        (vi)     Each Definitive Bearer Note initially delivered with Coupons
                 attached thereto should be surrendered for final redemption
                 together with all unmatured Coupons appertaining thereto,
                 failing which the amount of all missing unmatured Coupons (or,
                 in the case of a partial payment of principal, that proportion
                 of the aggregate amount of the missing unmatured Coupons that
                 the principal paid bears to the principal due) will be
                 deducted from the amount otherwise payable on such final
                 redemption, the amount so deducted being payable against
                 surrender of the relevant Coupon at the specified office of
                 any of the Paying Agents outside the United States and its
                 possessions at any time prior to the third anniversary of the
                 due date of such final redemption.

(c)      PAYMENTS-REGISTERED NOTES:

         (i)     This Condition 7(c) is applicable in relation to Notes
                 specified in the relevant Pricing Supplement as being in
                 registered form.

        (ii)     Payments of amounts (including accrued interest) due on the
                 final redemption of Registered Notes will be made against
                 presentation and, save in the case of partial redemption by
                 reason of insufficiency of funds, surrender of the relevant
                 Registered Notes at the specified office of a Transfer Agent.
                 If the due date for payment of the final redemption amount of
                 Registered Notes is not a Business Day, the Holder thereof
                 will not be entitled to payment thereof until the next
                 following Business Day and no further payment shall be due in
                 respect of such delay save in the event that there is a
                 subsequent failure to pay in accordance with these Conditions.

       (iii)     Payment of amounts (whether principal, interest or otherwise)
                 due (other than in respect of the final redemption amount of
                 Registered Notes) in respect of Registered Notes will be paid
                 to the Holders thereof as appearing in the register kept by
                 the Registrar as at opening of business (New York time) on the
                 fifteenth Business Day before the due date for such payment
                 (the "Record Date").
<PAGE>   16
        (iv)     Notwithstanding the provisions of Condition 7(c)(ii) payments
                 of principal, interest or otherwise due other than in respect
                 of a final redemption of Registered Notes will be made by a
                 cheque drawn on a bank in the Relevant Financial Center and
                 posted to the address (as recorded in the register held by the
                 Registrar) of the Holder thereof unless the Holder thereof has
                 applied to any Transfer Agent at least 15 days prior to the
                 relevant payment date and the New York Transfer Agent has
                 acknowledged such application for payment to be made to a
                 designated account.

For the purposes of these Conditions:

         (A)     "Business Day" means (unless varied or restated in the
                 relevant Pricing Supplement) a day on which commercial banks
                 and foreign exchange markets settle payments in the relevant
                 currency in London and, in the case of Registered Notes, New
                 York City and (x) which is a day on which commercial banks are
                 open and foreign exchange markets settle payments in the
                 relevant currency in the Relevant Financial Center, and (y) in
                 relation to payments due upon presentation and/or surrender of
                 any Notes or Coupons, in the relevant place of presentation
                 and/or surrender and (z) on which Cedel and Euroclear and, in
                 the case of Registered Notes, DTC are in operation; and

         (B)     "Relevant Financial Center" means (x) in relation to Notes
                 denominated in United States dollars, New York City, and (y)
                 in relation to Notes denominated in any other currency, such
                 financial center or centers as may be specified in relation to
                 the relevant currency and for the purposes of the definition
                 of "Business Day" in the 1991 ISDA Definitions (as amended and
                 updated from time to time), as published by the International
                 Swap Dealers Association, Inc.;

and, in all cases, as the same may be modified in the relevant Pricing
Supplement.

(d)      PAYMENTS SUBJECT TO FISCAL LAWS:  All payments are subject in all
cases to any applicable fiscal or other laws and regulations, but without
prejudice to the provisions of Condition 8.  No commissions or expenses shall
be charged to the Noteholders or Couponholders in respect of such payments.

(e)      PAYING AGENTS:  The initial Paying Agents, Issue Agent, Transfer
Agents and Registrar and their initial specified offices are listed below.  The
Issuer reserves the right at any time with the prior approval of the Trustee to
vary or terminate the appointment of any Paying Agent, Transfer Agent or the
Registrar and appoint additional or other Paying Agents, Transfer Agents or
Registrar provided that it will maintain (i) while Bearer Notes remain
outstanding, a Principal Paying Agent in a western European city; (ii) a
Registrar having a specified office in Buenos Aires so long as the Comision
Nacional de Valores (the "CNV") so requires; (iii) while Registered Notes
remain outstanding, a Paying Agent having a specified office in New York City;
(iv) a Paying Agent and a Transfer Agent having a specified office in
Luxembourg, so long as, in the case of the Paying Agent, Bearer Notes or
Registered Notes, or in the case of the Transfer Agent, Registered Notes of
such Series are listed on the Luxembourg Stock Exchange and the rules of such
exchange so requires; and (v) while Registered Notes remain outstanding, a
Transfer Agent having a specified office in New York City.  The Paying Agents,
the Transfer Agents, the Issue
<PAGE>   17
Agent and the Registrar reserve the right at any time to change their
respective specified office to some other specified office in the same city.
Notice of any change in the Paying Agents, the Transfer Agents or the Registrar
or their specified offices will promptly be given to the Noteholders and the
Issuer will notify the CNV.

(f)      REPAYMENT TO THE ISSUER:  All monies paid by or on behalf of the
Issuer to the Principal Paying Agent for the payment of principal of, or
interest on, any Note which remains unclaimed at the end of the Prescription
Period (as defined in Condition 10) in relation to such monies will be repaid
to the Issuer upon the Issuer's written request therefor and the holder of such
Note will thereafter look only to the Issuer for payment.  Upon such payment
all liability of the Principal Paying Agent with respect thereto shall
thereupon cease, without, however, limiting in any way the obligation of the
Issuer in respect of the amount so repaid.

(g)      FOREIGN EXCHANGE RESTRICTIONS:  Payments in respect of the Notes shall
be made in the currency of such Note as at the time of payment shall be legal
tender for the payment of public and private debts in that currency.  In the
event that on any payment date in respect of the Notes any restrictions or
prohibition of access to the Argentine foreign exchange market exists, the
Issuer agrees to pay all amounts payable under the Notes in the currency of
such Notes either (i) by purchasing with Argentine pesos, any series of "Bonos
Externos de la Republica Argentina" (U.S.  dollar-denominated Argentine
Government Bonds or "Bonex") or any other securities or public or private bonds
issued in Argentina, and transferring and selling such instruments outside
Argentina in exchange for the currency of such Notes; or (ii) by means of any
other legal procedure existing in Argentina, on any due date for payment under
the Notes, for the purchase of the currency of such Notes.  All costs and taxes
payable in connection with the procedures referred to in (i) and (ii) above
shall be borne by the Issuer.

8.       TAXATION

All amounts payable (whether in respect of principal, interest or otherwise) in
respect of the Notes and the Coupons shall be paid free and clear of, and
without withholding or deduction for, any taxes, duties, assessments or
governmental charges of whatever nature imposed, levied, collected, withheld or
assessed by or within Argentina or any authority or agency therein or thereof
having power to tax, unless such withholding or deduction is required by law.
In that event the Issuer shall pay such additional amounts ("Additional
Amounts") as will result in receipt by the Noteholders and the Couponholders of
such amounts as would have been received by them had no such withholding or
deduction been required, except that no such Additional Amounts shall be
payable in respect of any Note or Coupon:

         (a)     to a Holder (or third party on behalf of a Holder) where such
                 Holder is liable to such taxes, duties, assessments or
                 governmental charges in respect of such Note or Coupon by
                 reason of his having some connection with Argentina other than
                 the mere holding of the Note or Coupon; or

         (b)     presented for payment more than 30 days after the Relevant
                 Date except to the extent that the Holder of it would have
                 been entitled to such additional amounts on presenting such
                 Note or Coupon for payment on the last day of such period of
                 30 days.
<PAGE>   18
"Relevant Date" means in relation to any payment, whichever is the later of (i)
the date on which such payment first becomes due and (ii) if the full amount
payable has not been received by the Principal Paying Agent or the Trustee on
or prior to such due date, the date on which, the full amount having been so
received, prompt notice to that effect shall have been given to the Noteholders
by the Principal Paying Agent or the Trustee, in each case on behalf of the
Issuer.  Any reference in these Conditions to principal and/or interest shall
be deemed to include any Additional Amounts which may be payable under this
Condition or any undertaking given in addition to or, pursuant to Condition
12(d), in substitution for it under the Trust Deed.

In the event that the Issuer pays any Personal Property Tax pursuant to the
Argentine Personal Property Tax Law No.  23,966, as amended from time to time
(the "Personal Property Tax Law"), and its implementing Decree No. 127/96, as
amended from time to time, in respect of any Notes or Coupons, the Issuer has
agreed to waive any right it may have under Argentine law to seek reimbursement
(by way of any legal means available to the Issuer, including, without
limitation, deduction from payments of principal or interest on any Note or
Coupon) from the Holder of any Note or Coupon or beneficial owner of any
interest therein.

The tax treatment applicable to the Notes under Argentine tax law is that set
forth in the Negotiable Obligations Law, in Decree No. 2,284/91, Decree No.
1,076/92, Decree No. 1,684/93, Decree No. 1,802/93 and other applicable
Argentine laws and regulations.

9.       EVENTS OF DEFAULT

If any of the following events occurs the Trustee at its discretion may, and if
so requested by holders of at least one-fifth in principal amount of the Notes
then outstanding or if so directed by an Extraordinary Resolution shall, give
notice to the Issuer that the Notes of that Series are, and they shall
immediately become, due and payable at their principal amount together with
accrued interest:

         (a)     Non-payment:  the Issuer fails to pay any interest on or
                 principal of any of the Notes when due; or

         (b)     Breach of other obligations:  the Issuer does not perform or
                 comply with any one or more of its other obligations in the
                 Notes or the Trust Deed which default is incapable of remedy
                 or, if in the opinion of the Trustee capable of remedy, is not
                 in the opinion of the Trustee remedied within 30 days after
                 notice of such default shall have been given to the Issuer by
                 the Trustee; or

         (c)     Cross default:  (i) any other present or future indebtedness
                 of the Issuer or any of its Subsidiaries for or in respect of
                 moneys borrowed or raised becomes (or becomes capable of being
                 declared) due and payable prior to its stated maturity
                 otherwise than at the option of the Issuer; or (ii) any such
                 indebtedness is not paid when due or, as the case may be,
                 within any applicable grace period; or (iii) the Issuer or any
                 of its Subsidiaries fails to pay when due any amount payable
                 by it under any present or future guarantee for, or indemnity
                 in respect of, any monies borrowed or raised; provided that
                 the
<PAGE>   19
                 aggregate amount of the relevant indebtedness, guarantees and
                 indemnities in respect of which one or more of the events
                 mentioned above in this paragraph (c) have occurred equals or
                 exceeds U.S.$8,000,000 or its equivalent (as reasonably
                 determined by the Trustee); or

         (d)     Enforcement proceedings:  a distress, attachment, execution,
                 seizure before judgment or other legal process is levied,
                 enforced or sued out on or against any part of the property,
                 assets or revenues of the Issuer or any of its Subsidiaries
                 and (i) such distress, attachment, execution, seizure before
                 judgment or other legal process is not discharged or stayed
                 within 60 days of having been notified to the Issuer or any of
                 its Subsidiaries, as the case may be; or (ii) if such
                 distress, attachment, execution, seizure before judgment or
                 other legal process shall not have been discharged within such
                 60-day period, the Issuer or any of its Subsidiaries, as the
                 case may be, shall have within such 30-day period contested in
                 good faith by appropriate proceedings upon stay of execution
                 of the enforcement thereof or upon posting a bond in
                 connection therewith; provided, however, that in no event
                 shall the grace period provided by subclause (ii) of this
                 paragraph (d) extend beyond the 360th day after the
                 notification to the Issuer or any of its Subsidiaries, as the
                 case may be, of such proceedings; or

         (e)     Security enforced:  any mortgage, charge, pledge, lien or
                 other encumbrance, present or future, created or assumed by
                 the Issuer or any of its Subsidiaries becomes enforceable and
                 any step is taken to enforce it (including the taking of
                 possession or the appointment of a receiver, administrative
                 receiver, manager or other similar Person); or

         (f)     Insolvency:  the Issuer or any of its Subsidiaries is (or is,
                 or could be, deemed by law or a court to be) insolvent or
                 bankrupt or unable to pay its debts, stops, suspends or
                 threatens to stop or suspend payment of all or a material part
                 of (or of a particular type of) its debts, proposes or makes
                 any agreement for the deferral, rescheduling or other
                 readjustment of all of (or all of a particular type of) its
                 debts (or of any part which it will or might otherwise be
                 unable to pay when due), proposes or makes a general
                 assignment or an arrangement or composition with or for the
                 benefit of the relevant creditors in respect of any such debts
                 or a moratorium is agreed or declared in respect of or
                 affecting all or any part of (or of a particular type of) the
                 debts of the Issuer or any of its Subsidiaries; or

         (g)     Winding up:  an order is made or an effective resolution
                 passed for the winding up or dissolution or administration of
                 the Issuer or any of its Subsidiaries, or the Issuer ceases or
                 threatens to cease to carry on all or a material part of its
                 business or operations, except for the purpose of and followed
                 by a reconstruction, amalgamation, reorganization, merger,
                 demerger or consolidation (i) on terms approved by the Trustee
                 or by an Extraordinary Resolution of the Noteholders; or (ii)
                 in the case of a Subsidiary, whereby the undertaking and the
                 assets of the Subsidiary are transferred to or otherwise
                 vested in the Issuer or another of its Subsidiaries; or
<PAGE>   20
         (h)     Authorizations and consents:  any action, condition or thing
                 (including the obtaining or effecting of any necessary
                 consent, approval, authorization, exemption, filing, license,
                 order, recording or registration) at any time required to be
                 taken, fulfilled or done in order (i) to enable the Issuer
                 lawfully to enter into, exercise its rights and perform and
                 comply with its obligations under, the Notes and the Trust
                 Deed; (ii) to ensure that those obligations are legally
                 binding and enforceable; and (iii) to make the Notes and the
                 Trust Deed admissible in evidence in the courts of Argentina,
                 is not taken, fulfilled or done; or

         (i)     Illegality:  it is or will become unlawful for the Issuer to
                 perform or comply with any one or more of its obligations
                 under any of the Notes or the Trust Deed; or

         (j)     Revocation of pipeline license:  the Issuer's license to
                 operate the southern pipeline network is suspended or revoked;
                 or

         (k)     Analogous events:  any event occurs which under the laws of
                 any relevant jurisdiction has an analogous effect to any of
                 the events referred to in any of the foregoing paragraphs;

provided that in the case of paragraphs (b), (d), (e), (h) and (k) and, in the
case of Subsidiaries only, paragraphs (f) and (g), the Trustee shall have
certified that in its opinion such event is materially prejudicial to the
interests of the Noteholders.

10.      PRESCRIPTION

Claims in respect of principal and interest in respect of Notes will become
prescribed unless made as required by Condition 6 within a period (the
"Prescription Period") of three years from the appropriate Relevant Date.

11.      REPLACEMENT OF NOTES AND COUPONS

If any Note or Coupon is lost, stolen, mutilated, defaced or destroyed it may
be replaced at the specified office of the Issue Agent (in the case of Bearer
Notes and Coupons) or of the New York Transfer Agent (in the case of Registered
Notes), subject to all applicable laws and stock exchange requirements,
including the laws and regulations of Argentina, upon payment by the claimant
of the expenses incurred in connection with such replacement and on such terms
as to evidence, security, indemnity and otherwise as the Issuer and the Issue
Agent or, as the case may be, the New York Transfer Agent may require.
Mutilated or defaced Notes or Coupons must be surrendered before replacements
will be issued.  The Comision Nacional de Valores shall be notified by the
Issuer of any replacements made under this Condition.
<PAGE>   21
12.      MEETINGS OF NOTEHOLDERS, MODIFICATION, WAIVER AND SUBSTITUTION

(a)      MEETINGS OF NOTEHOLDERS:  The Trust Deed contains provisions for
convening meetings of Noteholders of any Series in London and Buenos Aires to
consider matters affecting their interests, including the sanctioning by
Extraordinary Resolution of a modification of any of these Conditions or any
provisions of the Trust Deed.  Such a meeting may be convened by Noteholders
holding not less than 5% in principal amount of the Notes of such Series for
the time being outstanding.  The quorum for any meeting convened in London or
Buenos Aires to consider an Extraordinary Resolution will be, in the case of
any meeting in London, two or more persons or, in the case of any meeting in
Buenos Aires, one or more persons holding or representing not less than 60% of
the Notes of such Series for the time being outstanding, or at any adjourned
meeting, in the case of any meeting in London, two or more persons or, in the
case of any meeting in Buenos Aires, one or more persons holding or
representing not less than 30% of the Notes of such Series for the time being
outstanding.  Any proposals to be considered at any meeting convened in London
or Buenos Aires which, inter alia, (i) postpone the maturity of the Notes of
any Series or the dates on which interest is payable in respect of the Notes of
any Series; (ii) reduce or cancel the principal amount of, or interest on, the
Notes of any Series; or (iii) change the currency of payment of the Notes or
the Coupons of any Series, must be passed by means of an Extraordinary
Resolution of Noteholders of such Series.  Any proposals to be considered at
any meeting convened in London or Buenos Aires to (i) substitute the Issuer (or
any previous substitute) as the principal debtor under the Trust Deed and the
Notes, or (ii) modify the provisions concerning the quorum required at any
meeting of Noteholders or the majority required to pass an Extraordinary
Resolution, must be passed by means of an Extraordinary Resolution of
Noteholders of all outstanding Notes.  Any resolution duly passed at a meeting
convened in London shall be binding on all Noteholders of the relevant Series
(whether or not they were present or represented at the meeting at which such
resolution was passed) and on all Couponholders, only upon ratification by a
meeting of Noteholders of the relevant Series held in Buenos Aires in
accordance with the provisions of the Negotiable Obligations Law which
provides, inter alia, that any resolution to ratify any of the proposals
mentioned above requires unanimous approval of those Noteholders, present or
represented and voting.  The Trust Deed contains provisions for Noteholders
present or represented at meetings in London to appoint proxies at meetings of
Noteholders in Buenos Aires.  Any resolution duly passed at a meeting convened
in Buenos Aires in accordance with the provisions of the Negotiable Obligations
Law shall be binding on all Noteholders of the relevant Series (whether or not
they were present or represented at such meeting, held in accordance with
Article 14 of the Negotiable Obligations Law, at which such resolution was
passed) and on all Couponholders.

(b)      MODIFICATION AND WAIVER:  The Trustee may agree, without the consent
of the Noteholders or Couponholders, to (i) any modification of any of the
provisions of the Trust Deed which is of a formal, minor or technical nature or
is made to correct a manifest error; and (ii) any other modification (except as
mentioned in the Trust Deed), and any waiver or authorization of any breach or
proposed breach, of any of the provisions of the Trust Deed which is in the
opinion of the Trustee not materially prejudicial to the interests of the
Noteholders.  Any such modification, authorization or waiver shall be binding
on the Noteholders and the Couponholders and, if the Trustee so requires, such
modification shall be notified to the Noteholders as soon as practicable.
<PAGE>   22
(c)      SUBSTITUTION:  The Trust Deed contains provisions permitting the
Trustee to agree, subject to such amendment of the Trust Deed and such other
conditions as the Trustee may require, and upon obtaining the approval of the
Noteholders by way of an Extraordinary Resolution, to the substitution of any
other company in place of the Issuer, or of any previous substituted company,
as principal debtor under the Trust Deed and the Notes.  The CNV shall be
notified by the Issuer of any substitution made under this Condition 12(c).

(d)      ENTITLEMENT OF THE TRUSTEE:  Without prejudice to Condition 8, in
connection with the exercise of its functions (including but not limited to
those referred to in this Condition) the Trustee shall have regard to the
interests of the Noteholders as a class and shall not have regard to the
consequences of such exercise for individual Noteholders or Couponholders and
the Trustee shall not be entitled to require, nor shall any Noteholder or
Couponholder be entitled to claim, from the Issuer any indemnification or
payment in respect of any tax consequence of any such exercise upon individual
Noteholders or Couponholders.

13.      ENFORCEMENT

At any time after the Notes become due and payable, the Trustee may, at its
discretion and without further notice, institute such proceedings against the
Issuer as it may think fit to enforce the terms of the Trust Deed, the Notes
and the Coupons, but it need not take any such proceedings unless (i) it shall
have been so directed by an Extraordinary Resolution or so requested in writing
by Noteholders holding at least one-fifth in principal amount of the Notes
outstanding; and (ii) it shall have been indemnified to its satisfaction.
Notwithstanding the above, any Noteholder or Couponholder may institute
proceedings directly against the Issuer in accordance with the provisions of
the Negotiable Obligations Law; but the Trust Deed contains provisions
excluding in those circumstances the Notes or Coupons of such Noteholder or
Couponholder from the benefits of the trusts contained in the Trust Deed.  No
Note or Coupon which has been the subject of proceedings under the Negotiable
Obligations Law may be presented to a Paying Agent for payment or to the Paying
or Transfer Agents for replacement but the Issuer has in the Trust Deed
covenanted to make separate arrangements for payment directly to the holder of
each such Note or Coupon.  If any Noteholder or Couponholder, having instituted
proceedings directly against the Issuer in accordance with the provisions of
the Negotiable Obligations Law, subsequently disposes of the Note or Coupon
forming the subject matter of such proceedings, the cessation of the rights
under the trusts created by the Trust Deed occurring upon the institution of
such proceedings, shall enure in relation to the purchaser of such Note or
Coupon.  Upon notification by the Issuer, the Trustee shall give notice to the
Paying and Transfer Agents of the certificate numbers of those Notes or Coupons
forming the subject matter of such proceedings and the Paying Agents, in
respect of Bearer Notes, and the Transfer Agents, in respect of Registered
Notes, shall make such certificate numbers available to any Noteholder or
potential Noteholder upon its request.

14.      INDEMNIFICATION OF THE TRUSTEE

The Trust Deed contains provisions for the indemnification of the Trustee and
for its relief from responsibility.  The Trustee and its parent, subsidiaries
and affiliates are entitled to enter into business transactions with the Issuer
and any entity related to the Issuer without accounting for any profit.
<PAGE>   23
15.      NOTICES

(a)      TO HOLDERS OF BEARER NOTES:  Notices to Holders of Bearer Notes will,
save where another means of effective communication has been specified in the
relevant Pricing Supplement, be valid if published (a) in a leading newspaper
having general circulation in Buenos Aires (which is expected to be La Nacion)
and otherwise in accordance with the provisions of the Negotiable Obligations
Law, (b) in a leading newspaper having general circulation in London (which is
expected to be the Financial Times), and (c) (so long as the Notes are listed
on the Luxembourg Stock Exchange and the rules of such exchange so requires) in
a leading newspaper having general circulation in Luxembourg (which is expected
to be the Luxemburger Wort) or, if in the opinion of the Trustee such
publication shall not be practicable, in an English language newspaper of
general circulation in Europe approved by the Trustee or, in the case of a
Temporary Global Note or Permanent Global Note, if delivered to Euroclear and
Cedel for communication by them to the persons shown in their respective
records as having interests therein provided that, in the case of Notes listed
on the Luxembourg Stock Exchange, the requirements of that Stock Exchange shall
have been complied with.  Any such notice shall be deemed to have been given on
the date of such publication or, if published more than once or on different
dates, on the first date on which publication is made or, as the case may be,
on the fourth Business Day after the date of such delivery.  Couponholders will
be deemed for all purposes to have notice of the contents of any notice given
to the Holders of Bearer Notes in accordance with this Condition.

(b)      TO HOLDERS OF REGISTERED NOTES:  Notices to Holders of Registered
Notes will be deemed to be validly given if (i) sent by first class mail to
them (or, in the case of joint Holders, to the first-named in the Register kept
by the Registrar) at their respective addresses as recorded in the register
kept by the Registrar, and will be deemed to have been validly given on the
fourth Business Day after the date of such mailing; (ii) published as may be
required by applicable law or, to the extent there are Argentine Holders of
Registered Notes (a) in the Official Gazette of Argentina and (b) in a leading
newspaper having general circulation in Buenos Aires (which is expected to be
La Nacion); and (iii) in the case of Registered Notes listed on the Luxembourg
Stock Exchange, the requirements of such exchange shall have been complied
with.

16.      GOVERNING LAW

(a)      GOVERNING LAW:  Argentine Negotiable Obligations Law No. 23,576, as
amended by Law No. 23,962, governs the requirements for the Notes to qualify as
Obligaciones Negociables thereunder while such law, together with the Argentine
Business Companies Law No. 19,550, as amended, and other applicable Argentine
law and regulations, govern the capacity and corporate authorizations of the
Issuer to execute and deliver the Notes and the authorization of the public
offering of the Notes by the CNV.  Notwithstanding the foregoing, the Trust
Deed, the Notes and the Coupons are governed by and shall be construed in
accordance with English law.

(b)      JURISDICTION:  In relation to any legal action or proceedings arising
out of or in connection with the Notes and the Coupons ("Proceedings"), the
Issuer has in the Trust Deed irrevocably submitted to the jurisdiction of the
courts of England.

(c)      AGENT FOR SERVICE OF PROCESS:  The Issuer has in the Trust Deed
appointed an agent in England to receive service of process in any Proceedings
in England based on any of the Notes or the Coupons.
<PAGE>   24
EXECUTED as a deed by                      )
TRANSPORTADORA DE GAS DEL SUR S.A.         )
acting by

  JOSE J.C. CONFORTI                       )
  ALEJANDRO BASSO                          )




THE COMMON SEAL of                         )
CITICORP TRUSTEE COMPANY LIMITED           )
was affixed                                )
in the presence of:                        )



HUW REES                             Signature of director
----------------------------

                                     Name of director
----------------------------




LEIGH COBB                           Signature of authorized signatory
----------------------------


                                     Name of authorized signatory
----------------------------