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                                                                     EXHIBIT 4.3

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                               Dated 15 July 2001

                                     E.ON AG

                                       and

                                    BP P.L.C.





                       GELSENBERG PARTICIPATION AGREEMENT





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                       THIS PARTICIPATION AGREEMENT ("PA")



between

BP P.L.C. of Britannic House, 1 Finsbury Circus, London EC2M 7BA ("BP");

and

E.ON AG of Bennigsenplatz 1, D-40474 Dusseldorf ("E.ON").



NOW, THEREFORE, the parties agree as follows:

1        DEFINITIONS

         "ACCOUNTS" means the audited accounts of Ruhrgas and the unaudited
         accounts of Gelsenberg which are attached to the Disclosure Letter in
         the Agreed Form;

         "AGREED FORM" means in relation to any document the form thereof
         initialled by or on behalf of E.ON and BP for the purposes of
         identification only;

         "BALANCE SHEET DATE" means 31 December 2000;

         "BEST OF BP'S KNOWLEDGE" means the actual knowledge of Dr Uwe Franke,
         Peter Knoedel and Dr Horstguenter Schulz;

         "BUSINESS DAY" means a day on which banks are open for business in both
         London and Dusseldorf (excluding Saturdays, Sundays and public
         holidays);

         "DEUTSCHE BP" means Deutsche BP Aktiengesellschaft whose registered
         office is at Hamburg;

         "BP GROUP" means BP and those companies in which BP holds, directly or
         indirectly, a majority shareholding;

         "DISCLOSURE LETTER" means the letter of even date with this Agreement
         from BP to E.ON (together with its attachments) disclosing information
         against the warranties in Schedule 1;

         "EFFECTIVE DATE" means 31 December 2001, 24:00 hours (German time)/1
         January 2002, 00:00 hours (German time) or if later the first calendar
         day in the month following the month in which the Required Approvals
         are obtained unless otherwise agreed by E.ON and BP;

         "EMPLOYEE BENEFITS ARRANGEMENTS" means benefit schemes (other than
         mandatory state arrangements and collective bargaining agreements)
         including, but not limited to, arrangements on (i) retirement, death,
         termination of employment (whether or not voluntary) or during periods
         of sickness or disablement or for life assurance, accidental death and
         injury including the supplementary systems of pension provision in any
         jurisdiction; (ii) medical benefits; (iii) termination indemnity or
         redundancy payments; or (iv) employee share option schemes;

         "E.ON GROUP" means E.ON and those companies in which E.ON holds,
         directly or indirectly, a majority shareholding;



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         "GELSENBERG" means Gelsenberg Aktiengesellschaft whose registered
         office is in Hamburg;

         "GELSENBERG GROUP" or "GELSENBERG GROUP COMPANIES" means Gelsenberg and
         those companies in which Gelsenberg holds, directly or indirectly, a
         majority shareholding and "GELSENBERG GROUP COMPANY" means any one of
         them;

         "JOINT VENTURE" means the joint venture to be established by E.ON and
         BP pursuant to this PA in relation to Gelsenberg;

         "LIBOR" means, in relation to any period (a "RELEVANT LIBOR PERIOD") in
         respect of which an interest rate is to be determined pursuant to this
         PA:;

         (i)      the rate per annum of the offered quotation for three-month
                  deposits in Euros which appears on the Telerate Screen soon
                  after 11:00 (London time) providing the rate as at 11 a.m. on
                  the APPLICABLE RATE FIXING DAY; or

         (ii)     if no such offered quotation appears on the Telerate Screen at
                  or about such time (or there is then no such Telerate Screen),
                  such rate as is equal to the arithmetic mean (rounded upwards,
                  if necessary, to seven decimal places) of the offered
                  quotations for daily Euro deposits which appear on the Reuters
                  Screen LIBO page (or such other page(s) as may replace the
                  LIBO page for the purpose of displaying offered rates of
                  leading reference banks in London for interbank daily deposits
                  in Euros) soon after 11:00 (London time) providing the rate as
                  at 11:00 (London time) on the APPLICABLE RATE FIXING DAY; or

         (iii)    if no such offered quotation appears on the Telerate Screen
                  (or there is then no such Telerate Screen) and no such offered
                  quotations appear on the Reuters Screen LIBO page or such
                  replacement page(s) as aforesaid (or there is then no such
                  LIBO page nor any replacement therefore), such rate as is
                  equal to the arithmetic mean (rounded upwards, if necessary,
                  to seven decimal places) of the respective rates (as quoted to
                  the paying party at its request) at which Barclays Bank PLC
                  and Royal Bank of Scotland plc are offering daily Euro
                  deposits for the Relevant Libor Period at or about 11:00
                  (London time) on the APPLICABLE RATE FIXING DAY.

         For the purposes of this definition the Telerate Screen means the
         display designated as on the Telerate Service such other service as may
         be nominated by the British Bankers' Association as the information
         vendor for the purpose of displaying British Bankers' Association
         Interest Settlement Rates for daily deposits in Euros), and "APPLICABLE
         RATE FIXING DAY" in relation to any Relevant Libor Period means the
         second Business Day preceding the first day of such Relevant Libor
         Period;

         "RUHRGAS" means Ruhrgas Aktiengesellschaft;

         "SENIOR EMPLOYEES" means any employees or consultants employed or
         engaged in the business of the Gelsenberg Group on an annual
         pensionable salary or fee in excess of Euro 125,000 (Euro one hundred
         and twenty-five thousand);

         "SHAREHOLDERS AGREEMENT" means the Agreement to be entered into by
         Deutsche BP and E.ON which reflects the principles set out in Schedule
         3;

         "SUBSCRIPTION DATE" means the date of subscription by E.ON of such
         newly issued shares in Gelsenberg representing 51 per cent. of the
         total shares of Veba Oel then in issue.



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         "VEBA OEL PARTICIPATION AGREEMENT" means the Agreement so called
         between E.ON and BP dated today's date;

2        CONDITIONS

2.1      The completion of this PA is subject to, and conditional upon, the
         satisfaction (or waiver by both parties) of each of the following
         conditions (the "REQUIRED APPROVALS"):

         2.1.1    if notification of the Joint Venture is required pursuant to
                  Council Regulations (EC) 4064/89 (the "ECMR"), the EC
                  Commission adopts a decision declaring either that the Joint
                  Venture falls outside the scope of the ECMR or, alternatively,
                  that the Joint Venture is compatible with the Common Market,
                  either unconditionally or subject to the fulfilment of certain
                  conditions or commitments if the fulfilment of such conditions
                  or commitments is reasonably acceptable to each of E.ON and
                  BP, or finally, the EC Commission does not adopt a decision
                  within the required time periods (the above decisions being
                  referred to as "ECMR APPROVAL"); and

         2.1.2    if competition authorities of individual member states of the
                  European Community ("NATIONAL AUTHORITIES") have otherwise
                  jurisdiction to examine the Joint Venture each National
                  Authority having such jurisdiction adopts a decision of
                  equivalent effect to any of those set out in Clause 2.1.1
                  (this clause being interpreted mutatis mutandis) (the
                  decisions in this Clause 2.1.2 being referred to as "NATIONAL
                  APPROVALS").

2.2      Each party shall use all reasonable endeavours to procure satisfaction
         of the conditions or commitments specified in Clause 2.1.

2.3      If the conditions specified in Clause 2.1 are not satisfied or waived
         by E.ON and BP prior to the date which is 18 months following the EC
         Commission or the National Authority taking jurisdiction over the
         transaction set out in this PA, then each party shall have the right to
         terminate this PA on or after such date without prior notice by
         notifying the other party in writing.

3        PROHIBITION ON TRANSFER

         Subject to this PA being terminated in accordance with clause 2.3 above
         BP shall not, and shall procure that no member of the Gelsenberg Group,
         does any of the following actions without the prior written consent of
         E.ON:

         (i)      issue, sell, transfer, dispose or otherwise encumber any
                  interest in the shares of Gelsenberg, any member of the
                  Gelsenberg Group Companies or in Ruhrgas;

         (ii)     incur or enter into any agreement or commitment involving in
                  aggregate any capital expenditure in excess of Euro 10 million
                  (other than in respect of usual care and maintenance capital
                  expenditure);

         (iii)    enter into any agreement or commitment to dispose of any
                  assets other than in the ordinary course of business;

         (iv)     incur any additional borrowings or incur any other
                  indebtedness if any such would not be in the ordinary course
                  of business;

         (v)      unless otherwise provided in this PA enter into, terminate or
                  amend any material agreements, including enterprise agreements
                  (Unternehmensvertrage), joint



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                  venture agreements, sales and supply agreements, other than in
                  the ordinary course of business;

         (vi)     make any material amendment to the terms and conditions of
                  employment (including remuneration, pension entitlements,
                  share option schemes) of any Senior Employee or dismiss any
                  Senior Employee or appoint any additional Senior Employees;

         (vii)    except as required by law or in connection with any mandatory
                  bargaining arrangements, amend any Employee Benefit
                  Arrangements to any material extent or communicate to any
                  employee any proposal to amend any such Employee Benefit
                  Arrangement other than in the ordinary course of business; or

         (viii)   make any amendment to any of the articles of association,
                  by-laws of the management or supervisory boards of any of the
                  Gelsenberg Group Companies.

4        ESTABLISHMENT OF JOINT VENTURE

4.1      Subject to the satisfaction or waiver of the Required Approvals, each
         of E.ON and BP agrees that E.ON shall subscribe for new shares in
         Gelsenberg within 10 Business Days of the Required Approvals having
         been satisfied or waived, but the parties agree that such subscription
         shall not be effective before the Effective Date, at such place and a
         time as agreed by E.ON and BP (the "SUBSCRIPTION DATE") and that the
         following steps shall be taken.

4.2      Subject to BP having satisfied its obligations under and procured the
         occurrence of the events pursuant to, Clause 4.2.2, on or prior to the
         Subscription Date, each of E.ON and BP agrees that it shall or shall
         procure that a member of the BP Group or the E.ON Group, respectively,
         carries out the following:

         4.2.1    Each of E.ON and Deutsche BP shall enter into the Shareholders
                  Agreement.

         4.2.2    The capital of Gelsenberg shall be increased by DM 104,081,630
                  to DM 204,081,630 and E.ON shall subscribe for the new shares.
                  The new shares shall be issued without stipulation of a higher
                  issue price (Ausgabebetrag) than their nominal value but by
                  agreement inter partes for a contribution in the aggregate
                  amount of Euro 2,497,959,184 (Euro two billion and four
                  hundred ninety-seven million nine hundred fifty-nine thousand
                  one hundred eighty-four) by combining the contribution of cash
                  and assets as follows:

                  (i)      Payment of the nominal amount of Euro 53,216,100 in
                           cash;

                  (ii)     The forgiveness of all shareholder loans of Deutsche
                           BP to Gelsenberg at the Effective Date to be
                           purchased by E.ON at face value. To the extent that
                           short-term shareholder loans should remain for
                           technical reasons, in particular loans on current
                           account which are not purchased by E.ON, E.ON and BP
                           will procure that any cash in the Gelsenberg Group
                           resulting from its operative income (only) will be
                           used to repay any such shareholder loan;

                  (iii)    The contribution of participations in E.ON Group
                           Companies not generating taxable income (the
                           participations or other assets to be so contributed
                           to be agreed by BP, such agreement not to be
                           unreasonably withheld or delayed; in particular,
                           without limitation, there shall be good reason for
                           withholding



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                           the agreement if the earnings resulting from such
                           contributions are dilutive compared to earnings from
                           the lending of a cash contribution at market terms);
                           and

                  (iv)     Cash, if needed, to make up any remaining balance
                           (provided that E.ON may subsequently procure that
                           Gelsenberg may use such cash to purchase debt
                           instruments and/or participations in any E.ON Group
                           Company on a basis to be agreed by BP, such agreement
                           not to be unreasonably withheld or delayed).

         4.2.3    To the extent that assets are contributed the parties shall
                  agree on their valuation prior to the signing of the
                  Shareholders Agreement. If the parties can not agree within
                  one month after E.ON has notified BP of the assets it wishes
                  to contribute, then E.ON shall within 2 weeks nominate three
                  certified accountancy firms of international reputation (the
                  "ACCOUNTANTS") to BP. BP shall then have two weeks to nominate
                  one such Accountant to value the assets. Once the Accountant
                  has been nominated and notified by E.ON and BP, it shall value
                  the assets within one month. The valuation determined by the
                  Accountant (acting as an expert and not an arbitrator) shall,
                  once notified, be binding on E.ON and BP. The cost of this
                  valuation shall be borne by both parties in equal proportions.

         4.2.4    As from January 1, 2002, or, if later, from the Effective
                  Date, E.ON and Deutsche BP shall share profits in proportion
                  to their respective participations in the nominal share
                  capital of Gelsenberg.

         4.2.5    If the Effective Date is later than 1 January 2002 each of
                  E.ON and BP shall procure on a basis and timetable to be
                  agreed that Gelsenberg's auditors appointed to audit the
                  Gelsenberg financial statements of 2001 draw up an audited
                  interim financial statement of the consolidated Gelsenberg
                  Group (based on German GAAP and consistent with the accounting
                  policies for the Accounts for the year ended 31 December 2000)
                  as of the Effective Date.

         4.2.6    Unless otherwise agreed by the parties or BP has waived its
                  rights to rescind this PA, each of E.ON and BP agrees that the
                  subscription by E.ON for the Gelsenberg shares pursuant to
                  Clause 4.2 shall be made simultaneously with a subscription by
                  Deutsche BP for the Veba Oel shares pursuant to the Veba Oel
                  Participation Agreement.

         4.2.7    E.ON and BP hereby agree that E.ON, subject to becoming a
                  shareholder in Gelsenberg, shall join and be bound by all
                  obligations of Deutsche BP pursuant to the agreement between
                  Deutsche BP and Ruhrkohle Aktiengesellschaft dated 4 December
                  1994 in accordance with Section 5 of that Agreement.

         4.2.8    Deutsche BP shall, to the extent legally permissible, procure
                  that

                  (i)      the majority of the members on the supervisory board
                           of Gelsenberg (to be nominated by Deutsche BP) shall
                           resign with effect from the Subscription Date,

                  (ii)     an equal number of E.ON nominees are elected by a
                           shareholders meeting of Gelsenberg as new members of
                           the supervisory board of Gelsenberg for the maximum
                           term permitted by law of which one is elected
                           chairman of the supervisory board,



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                  (iii)    the supervisory board of Gelsenberg appoints 3 E.ON
                           nominees as additional members to the management
                           board of Gelsenberg, one of which will be chairman of
                           the management board, which will comprise a total of
                           5 members, such additional members shall have equal
                           representation powers to the present members, and

                  (iv)     the Gelsenberg representative on the supervisory
                           board of Ruhrgas shall resign and be replaced by an
                           E.ON nominee.

         4.2.9    As from the Effective Date, to the extent legally permissible,
                  BP shall procure that, following consultation between E.ON and
                  Deutsche BP, Gelsenberg exercises its voting rights in
                  Bergemann GmbH and Ruhrgas in accordance with the instructions
                  of E.ON.

         4.2.10   Each of E.ON and BP shall, to the extent legally permissible,
                  support the appointment of each others nominees to the
                  supervisory board for the maximum period permitted by law.

         4.2.11   The parties shall procure that the by-laws (Geschaftsordnung)
                  of the supervisory board of Gelsenberg shall be amended in
                  accordance with Schedule 2.

         4.2.12   Each of E.ON, BP and Gelsenberg shall execute the BP Indemnity
                  Agreement incorporating the basic terms and conditions set out
                  in Schedule 4 (the "BP INDEMNITY");

         4.2.13   Each of E.ON, BP and Gelsenberg shall execute the Health,
                  Safety and Environmental Deed substantially in the form set
                  out in Schedule 5 (the "HSE DEED").

5        WARRANTIES

5.1      Prior to entering into this PA, E.ON has only performed a very high
         level review of the business of Gelsenberg, the results of which have
         been reflected in the determination of the consideration. Between 1
         September 2001 and 1 November 2001 E.ON will perform a due diligence
         review. This due diligence will cover verification by E.ON's auditors
         of the information exchanged as well as the legal basis of ownership or
         other rights with respect to major assets, and such other matters as
         agreed herein. E.ON shall be given access to the relevant auditors and
         senior management personnel (being the persons listed in the definition
         of Best of BP's Knowledge) of Gelsenberg in carrying out this review.

         5.1.1    BP hereby represents and warrants to E.ON as independent
                  guarantees (selbstandiges Garantieversprechen) that the
                  warranty statements in Schedule 1 are true and correct as of
                  the date hereof and as of the Effective Date. If the due
                  diligence should reveal or if it should turn out later that
                  the statements are not completely true and correct, BP shall
                  take all reasonable steps to ensure within one month that all
                  its representations and warranties will be correct or, if this
                  is not possible, shall make such an additional cash
                  contribution to Gelsenberg or, at the discretion of E.ON,
                  shall pay such an amount of cash to E.ON, as is necessary to
                  put Gelsenberg or E.ON, as the case may be, in the same
                  economic position it would have been in, had the
                  representations and warranties been true and correct.

         5.1.2    The right of E.ON to demand cash compensation to Gelsenberg or
                  E.ON for the breach or compensation in accordance with clause
                  5.1.1 shall exist only if the cash payable for breaches of a
                  representation and warranty (based on the 100 per cent




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                  payable if paid to Gelsenberg) exceeds an amount of Euro
                  3,000,000 (Euro three million) per individual item (or Euro
                  100,000,000 (Euro one hundred million) in the event of Clause
                  9.2 of Schedule 1) and the sum of the cash that would be
                  payable for all breaches that individually exceed Euro
                  3,000,000 (Euro three million) exceeds the amount of Euro
                  50,000,000 (Euro fifty million). If the thresholds are
                  exceeded, the full amount, not only the excess shall be
                  payable.

         5.1.3    The total of all claims under representations and warranties
                  pursuant to Schedule 1 shall be limited

                  (i)      any claims under warranties in Clause 1, 2, 4 and 5
                           shall be limited to the aggregate of Euro
                           2,400,000,000 (Euro two billion and four hundred
                           million) and the face value of the shareholder loans
                           purchased by E.ON pursuant to Section 4.2.2 (ii);

                  (ii)     any claims under the other warranties in Schedule 1
                           shall be limited to Euro 1,200,000,000 (Euro one
                           billion and two hundred million).

         5.1.4    E.ON shall not be entitled to claim any amounts under the
                  representations or warranties contained in Schedule 1 in
                  respect of any matter which is fairly and adequately set out
                  in the Disclosure Letter.

         5.1.5    For the avoidance of doubt, Sections 460, 464 of the German
                  Civil Code shall not apply. The parties agree that the legal
                  remedy for any breach of the warranties in Schedule 1 shall be
                  governed by this Clause 5 and not by any other general rule of
                  German law and there are no other explicit or implied
                  warranties as to the commercial, legal or financial situation
                  of the Gelsenberg Group other than as provided for in this PA
                  and its Annexures.

5.2      The representations and warranties in Schedule 1 shall be subject to a
         time limitation of two years from the Effective Date, except for the
         title warranties in clauses 1 to 4 of Schedule 1 for which a limitation
         period of 30 years shall apply.

5.3      BP agrees that as from the Effective Date Gelsenberg shall have the
         right to conduct of any legal proceedings brought by a third party
         against Gelsenberg which may result in a warranty claim by E.ON against
         BP under this PA (a "RELEVANT CLAIM") Provided That:

         (i)      E.ON shall procure that Gelsenberg will consult with BP on a
                  regular basis as to conduct of any Relevant Claim;

         (ii)     Gelsenberg shall not settle any such Relevant Claim without
                  the prior written consent of BP (such consent not to be
                  unreasonably withheld or delayed);

         (iii)    E.ON shall procure that Gelsenberg, at the reasonable request
                  of BP, will appeal (to the extent permitted) any first
                  instance decision which is in favour of a third party which
                  has brought a Relevant Claim.

5.4      To the extent possible, any payment required by this Clause 5 which is
         due after the Gelsenberg Completion Date shall be paid within 5
         Business Days of any final determination.



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6        EMPLOYEES

6.1      If the Gelsenberg Put Option is exercised and E.ON merges the
         Gelsenberg business with E.ON's business, then E.ON agrees to select
         the best people for the available positions subject to legal
         obligations with regard to non-managerial staff.

6.2      The cost of redundancies arising from any such merger of the businesses
         will be borne by E.ON.

7        E.ON POLICIES AND PRINCIPLES

         Save as otherwise provided in this PA, each of E.ON and BP agrees that
         as soon as practical following the Effective Date, Gelsenberg shall
         adopt the systems and processes, accounts, principles and policies of
         the E.ON Group, as from time to time amended.

8        DURATION AND EXIT

8.1      The Joint Venture shall be of unlimited duration and any proposed sale,
         transfer, disposal or encumbrance by either of E.ON and Deutsche BP of
         any part of its shares in Gelsenberg shall be subject to the prior
         written consent of the other shareholders in Gelsenberg.

8.2      Subject to the terms of this PA E.ON agrees that at any time on or
         after 1 January 2002 BP shall be entitled to put its entire
         shareholding in Gelsenberg consisting of1 million bearer shares with a
         nominal value of DM 100 each (the "GELSENBERG SHARES") onto E.ON (the
         "GELSENBERG PUT OPTION") in consideration for a fixed price of Euro
         2,400,000,000 (Euro two billion and four hundred million) subject to
         adjustment referred to in clause 9 below (the "GELSENBERG PUT OPTION
         AMOUNT").

8.3      If BP notifies E.ON that it wishes to exercise the Gelsenberg Put
         Option by the 10th Business Day of a calendar month then the completion
         date for economic transfer of the Gelsenberg Shares shall be the first
         calendar day of the month in which such notification is given to E.ON
         pursuant to this PA, otherwise the first calendar day of the following
         month (the "GELSENBERG ECONOMIC TRANSFER DATE").

8.4      Within 10 Business Days of such notification by BP, each of E.ON and BP
         shall procure that completion of the transfer of Deutsche BP's
         Gelsenberg Shares to E.ON so that E.ON shall be entitled to 100 per
         cent. of the income from the Gelsenberg Economic Transfer Date against
         payment by E.ON of the Gelsenberg Put Option Amount plus interest (if
         any) at LIBOR from and including the Gelsenberg Economic Transfer Date
         until (but excluding) the actual date of the transfer of the Gelsenberg
         Shares (such date being the "GELSENBERG COMPLETION DATE").

9        GELSENBERG PUT OPTION AMOUNT ADJUSTMENT

         Each of E.ON and BP agrees that the Gelsenberg Put Option Amount shall
         be adjusted to reflect the following:

9.1      a deduction of any amount validly claimed by E.ON and agreed by BP in
         respect of a breach of warranty by BP pursuant to clause 5.1 above in
         the period between signing this PA and the Gelsenberg Economic Transfer
         Date. If no agreement is reached, E.ON may still claim such amount as a
         breach of warranty pursuant to this Agreement;

9.2      an adjustment in respect of the amount which E.ON and BP shall agree
         represents:



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         9.2.1    Retained Earnings of the Gelsenberg Group on a consolidated
                  basis for the period from 1 January 2001 to the Gelsenberg
                  Economic Transfer Date. Retained Earnings means the earnings
                  of the Gelsenberg Group generated by its operations after
                  deduction of net interest, depreciation, amortisation,
                  taxation, minority interests and distributions.

                  (i)      Retained Earnings shall be calculated in accordance
                           with German GAAP and following Gelsenberg's existing
                           accounting policies, procedures and practices
                           consistently applied in drawing up the Gelsenberg
                           Group for the financial years ending on 31 December
                           2000, provided, however, that the actual dividend
                           paid by Ruhrgas to Gelsenberg in 2002 shall be
                           allocated pro rata temporis to each month of the
                           calendar year 2002 irrespective of whether such
                           dividend is paid before or after the Gelsenberg
                           Economic Transfer Date.

                  (ii)     Each of E.ON and BP agrees that if the Ruhrgas
                           dividend payable to Gelsenberg for 2002 has not been
                           paid at the Gelsenberg Economic Transfer Date, then
                           the parties shall agree an estimated dividend based
                           on the dividend paid by Ruhrgas to Gelsenberg for the
                           year ending 2001 which amount shall be subsequently
                           adjusted once the actual Ruhrgas dividend for 2002 is
                           paid.

         9.2.2    an agreed proportion of the revenue expenditure incurred by
                  the Gelsenberg Group in excess of the amount set out in the
                  Reserved Matters in respect of such revenue expenditure
                  otherwise than in the ordinary course of business.

9.3      To the extent possible, any payment required by this Clause 9 and due
         after the Gelsenberg Completion Date shall be paid within 5 Business
         Days of the agreement or determination of such adjustments. Such
         payments shall bear interest at LIBOR from (and including) the
         Gelsenberg Economic Transfer Date until (but excluding) the date of
         payment.

9.4      The relevant amounts as of the Gelsenberg Economic Transfer Date for
         calculation of the adjustments pursuant to Clause 9.2.1 shall be
         calculated on the basis of audited interim financial statements of the
         Gelsenberg Group proposed in accordance with Clause 4.2.5 above.

9.5      In order to reflect the estimated tax burden, each of E.ON and BP
         agrees that deductions and adjustments according to 9.1 and 9.2.2
         claimed in the period between Effective Date and Gelsenberg Completion
         Date on which payment is made as part of the Gelsenberg Put Option
         Amount shall be reduced by a lump sum amount of 40 per cent. of the
         aforementioned deduction and adjustment.

9.6      BP agrees to indemnify and hold E.ON harmless against any liability,
         loss or cost suffered by Gelsenberg as a result of AGIP failing to
         comply with its existing contractual obligations to make payments to
         Gelsenberg in respect of pensions and related costs of former employees
         of RVI.

10       CHANGE OF CONTROL OVER A SHAREHOLDER

         BP shall have the right to extraordinarily exercise the Gelsenberg Put
         Option pursuant to clause 8.2 effective at any time with a notice
         period of one month if there is a Change of Control over the respective
         shareholder in E.ON. For the purposes of this provision,

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         "CHANGE OF CONTROL" means that a person or company (including
         affiliated enterprises and third parties acting in concert with such
         person or company) acquires control of thirty per cent (30%) or more of
         the shares or voting rights in the company or corporation in question.

11       RESCISSION RIGHT

11.1     BP shall have the right to rescind this PA prior to the Subscription
         Date by notice in writing to E.ON if the Veba Oel transaction should
         have received a denial of the Required Approvals of the EC Commission
         or the National Authority (as the case may be) as defined in and
         pursuant to the Veba Oel Participation Agreement.

11.2     E.ON is aware of the pre-emption rights of Bergemann GmbH and Ruhrkohle
         Aktiengesellschaft pursuant to the two agreements between Deutsche BP
         and Ruhrkohle Aktiengesellschaft dated 27 April 1979. If Bergemann or
         Ruhrkohle Aktiengesellschaft exercise their pre-emption rights, BP
         shall have the right to rescind this PA.

12       CHANGE OF TAX LAW

         In case of any changes to the tax laws relevant for the transactions
         contemplated hereunder, each of E.ON and BP agrees to discuss in good
         faith any changes in the transaction's structure provided herein, which
         appear to avoid an unforeseeable tax burden, provided that neither BP
         nor E.ON shall be obliged to agree to any change detrimental to its tax
         or financial position which is not fully compensated.

13       MISCELLANEOUS

13.1     Where this PA or any of its Schedules requires any action to be taken
         by a member of the Gelsenberg Group or the E.ON Group, then BP or E.ON
         respectively, shall procure, to the extent legally permissible, that
         such acts are carried out or performed in accordance with the relevant
         provisions hereof.

13.2     E.ON'S AND BP'S LIABILITY

         Any reference in this PA (however expressed) to a liability or
         obligation of any member of the E.ON Group shall be deemed to
         incorporate a reference to an obligation on the part of E.ON to procure
         that the relevant liability is discharged or obligation is performed
         (notwithstanding that such member of the E.ON Group is not a party to
         this PA). Any reference in this PA (however expressed) to a liability
         or obligation of any member of the BP Group shall be deemed to
         incorporate a reference to an obligation on the part of BP to procure
         that the relevant liability is discharged or obligation is performed
         (notwithstanding that such member of the BP Group is not a party to
         this PA).

13.3     ASSIGNMENT

         This PA is personal to the parties to it. Accordingly, neither of BP or
         E.ON may, without the prior written consent of the other, assign the
         benefit of all or any of the obligations of any other party under this
         PA nor any benefit arising under or out of this PA.

13.4     VARIATION ETC.

         No variation of this PA shall be effective unless in writing and signed
         by or on behalf of each of the parties to this PA.







                                      -10-
<PAGE>

13.5     ANNOUNCEMENTS

         13.5.1   Subject to sub-clause 13.5.2, no announcement concerning this
                  PA shall be made by any of the parties without the prior
                  written approval of the other parties such approval not to be
                  unreasonably withheld or delayed.

         13.5.2   Any party may make an announcement concerning this PA if
                  required by:

                  (i)      the law of any relevant jurisdiction;

                  (ii)     any securities exchange or regulatory or governmental
                           body to which either party is subject or submits,
                           wherever situated, including (without limitation) the
                           Stock Exchange whether or not the requirement has the
                           force of law,

                  in which case the party concerned shall take all such steps as
                  may be reasonable and practicable in the circumstances to
                  agree the contents of such announcement with the other parties
                  before making such announcement.

13.6     CONFIDENTIALITY

         13.6.1   Subject to sub-clause 13.6.2, each party shall treat as
                  strictly confidential all information received or obtained as
                  a result of entering into or performing this PA which relates
                  to:

                  (i)      the provisions of this PA or any document referred to
                           in this PA; or

                  (ii)     the subject matter of this PA or any document
                           referred to in this PA.

         13.6.2   Any party may disclose information which would otherwise be
                  confidential if and to the extent:

                  (i)      required by the law of any relevant jurisdiction;

                  (ii)     required by any securities exchange or regulatory or
                           governmental body to which that party is subject or
                           submits (including on a new listing), wherever
                           situated, including (without limitation) the Stock
                           Exchanges, whether or not the requirement for
                           information has the force of law;

                  (iii)    the information has come into the public domain
                           through no fault of that party.

13.7     NOTICES

         Save to the extent otherwise provided in this PA:-

         13.7.1   any notice or other communication requiring to be given or
                  served under or in connection with this PA shall be in writing
                  and shall be sufficiently given or served if delivered or
                  sent:

                  In the case of E.ON to E.ON at:

                  E.ON Platz 1,
                  40479 Dusseldorf
                  Fax: (49) 211-4579 446
                  Attention: Vorstand

                  In the case of BP to BP at:





                                      -11-
<PAGE>


                  Britannic House
                  1 Finsbury Circus
                  London
                  EC2M 7BA

                  Fax: (44) 20 7496 4571

                  Attention: Jens Bertelsen

         13.7.2   any such notice or other communication shall be delivered by
                  hand or sent by courier, fax or prepaid first class post. If
                  sent by courier such notice or communication shall
                  conclusively be deemed to have been given or served on the
                  fifth Business Day following despatch. If sent by fax such
                  notice or communication shall conclusively be deemed to have
                  been given or served at the time of despatch. If sent by post
                  such notice or communication shall conclusively be deemed to
                  have been received seven Business Days from the time of
                  posting.

13.8     COUNTERPARTS

         This PA may be executed in any number of counterparts each of which
         shall be deemed an original, but all the counterparts shall together
         constitute one and the same instrument.

13.9     GOVERNING LAW AND ARBITRATION

         13.9.1   This PA and the Shareholders' Agreement shall be subject to
                  the substantive law of the Federal Republic of Germany.

         13.9.2   Any disputes arising in connection with this PA, the
                  Schedules, Appendices and Annexes thereto shall be settled by
                  an amicable effort on the part of E.ON and BP and if necessary
                  by reference to board members of E.ON and BP. If an attempt
                  for a settlement has not been successful within three months
                  from the date it was first requested, the disputes, including
                  those regarding the validity of the PA, shall be finally
                  settled in accordance with the arbitration rules of the DIS
                  with three arbitrators, the place of arbitration in Frankfurt,
                  and the language being English and all documents being in
                  English, without recourse to the ordinary courts of law. The
                  arbiters shall be qualified as judges in Germany.

         13.9.3   Unless otherwise agreed, each of E.ON and BP shall pay their
                  own legal and other fees, costs and expenses in connection
                  with the negotiation and execution of this PA and the
                  Shareholders' Agreement.

         13.9.4   In the event that any provision of this PA shall be or shall
                  become invalid, unenforceable or unworkable (undurchfuhrbar)
                  the remaining provisions shall not be affected thereby. The
                  invalid, unenforceable or unworkable provision shall be
                  replaced by a provision coming closest to what had been
                  intended by E.ON and BP in setting out the invalid,
                  unenforceable or unworkable provision, or would have been
                  intended by E.ON and BP had they considered the point. Any
                  omission shall be filled accordingly. Should the invalidity be
                  based on a measure of performance or time (time period, limit
                  or due date) it shall be adapted accordingly.





                                      -12-
<PAGE>

         15 July 2001                  15 July 2001

         BP p.l.c.:                    E.ON AG:

         Roger Skinner                 Ulrich Hartmann

                                       Michael Gaul




















                                      -13-
<PAGE>



                           SCHEDULE 1 - BP WARRANTIES



1        CAPACITY AND AUTHORITY

1.1      INCORPORATION AND EXISTENCE BP, Gelsenberg and Ruhrgas are duly
         incorporated, organised and validly existing under their respective
         laws of incorporation .

1.2      POWER AND AUTHORITY BP has the legal right and full power and authority
         to execute and deliver and to exercise its rights and perform its
         obligations under this PA and all the documents which are to be
         executed by BP as envisaged by this PA.

1.3      CORPORATE ACTION All corporate action required by BP to authorise the
         execution and delivery of and to exercise its rights and perform its
         obligations under this PA and all other documents which are to be
         executed by BP as envisaged by this PA has been taken.

1.4      BINDING AGREEMENTS This PA constitutes and all other documents which
         are to be executed by BP as envisaged by this PA, to the extent that BP
         is a party thereto, when executed will constitute valid and binding
         agreements enforceable in accordance with their respective terms.

1.5      NO BREACH The execution and delivery of and the performance by BP of
         its obligations under this PA and all other documents which are to be
         executed by BP as envisaged by this PA will not:

         (a)      result in a breach of any provision of the constitutional
                  documents of BP or Gelsenberg; or

         (b)      (save only as set out in this Disclosure Letter) result in a
                  breach of or give any third party a right to terminate or
                  modify, or result in the creation of any encumbrance,
                  pre-emption or similar right under, any agreement, licence,
                  permit or other instrument, order, judgement or decree of any
                  Court, governmental agency or regulatory body to which a
                  Gelsenberg Group Company or Ruhrgas is a party or by which any
                  of them is bound.

2        THE INTERESTS IN RUHRGAS, SCHUBERT KG AND BERGEMANN GMBH

         (Save only as set out in the Disclosure Letter) at the Gelsenberg
         Completion Date, Gelsenberg will be the legal and beneficial owner,
         free and clear of any third party rights or encumbrances, of
         Gelsenberg's interests in Ruhrgas, Schubert KG and Bergemann GmbH. The
         shares and interests have been properly and validly allotted and issued
         and are each fully paid.

3        THE NEW SHARES

         (Save only as set out in the Disclosure Letter) upon allotment of the
         new shares in Gelsenberg to E.ON in accordance with clause 4.2 of the
         PA (the "NEW SHARES"), E.ON will become the legal and beneficial owner,
         free and clear of any third party rights or of the New Shares and will
         hold 51 per cent of the entire issued and outstanding share capital of
         Gelsenberg.









                                      -14-
<PAGE>

4        THE GELSENBERG SHARES

         (Save only as set out in this Disclosure Letter) Deutsche BP is and
         upon exercise of the Gelsenberg Put Option pursuant to this PA will be
         entitled to sell and transfer to E.ON the full legal and beneficial
         ownership to the Gelsenberg Shares on the terms of this PA and all
         other documents which are to be executed by the parties as envisaged by
         this PA without the consent of any third party free and clear of any
         encumbrances or other third party rights. The Gelsenberg Shares have
         been properly and validly allotted and issued and are each fully paid.

5        OWNERSHIP OF THE GELSENBERG GROUP COMPANIES

         (Save as set out in the Disclosure Letter) Gelsenberg, directly or
         indirectly through another Gelsenberg Group Company, is the sole and
         beneficial owner of the issued or allotted shares of the companies
         listed in Appendix 1 (subject to any changes of a non-material nature
         since 31 December 2000) free from all encumbrances or other third party
         rights and all such shares are fully paid and non-assessable as set out
         in Appendix 1.

6        ACCOUNTS AND RECORDS

6.1      LATEST ACCOUNTS
         The Accounts have been prepared in accordance with applicable law and
         in accordance with accounting principles, standards and practices
         generally accepted at the date of their preparation in Germany and,
         subject thereto, on a basis consistent with that adopted in preparing
         the audited accounts for the previous two financial periods so as to
         fairly present the assets, liabilities and state of affairs of
         Gelsenberg and each of the Gelsenberg Group Companies and of the
         Gelsenberg Group Companies as a whole at the balance sheet date to
         which such Accounts relate and of the profits or losses for the period
         concerned, especially such issues as, but not limited to:

         6.1.1    full provision for all actual liabilities;

         6.1.2    proper provision (or note in accordance with good accountancy
                  practice) for all contingent liabilities;

         6.1.3    provision reasonably regarded as adequate for all bad and
                  doubtful debts; and

         6.1.4    disclosure of non-recurring items.

6.2      ACCOUNTING AND OTHER RECORDS
         The statutory books, books of account and other records of whatsoever
         kind of each Gelsenberg Group Company and Ruhrgas are up-to-date and
         maintained in accordance with all applicable legal requirements on a
         proper and consistent basis and contain complete and accurate records
         of all matters required to be dealt with in such books and all such
         books and records and all other documents (including documents of title
         and copies of all subsisting agreements to which any Gelsenberg Group
         Company or Ruhrgas is a party) which are the property of any Gelsenberg
         Group Company or Ruhrgas or ought to be in their possession are in
         their possession (or under their control) and no notice or allegation
         that any is incorrect or should be rectified has been received. In
         relation to the Gelsenberg Group Companies accounts, documents and
         returns required by law to be delivered or made to the Commercial
         Register or any other authority have been duly and correctly delivered
         or made.








                                      -15-
<PAGE>

7        ABSENCE OF UNDISCLOSED LIABILITIES

         There are no liabilities of the Gelsenberg Group Companies or Ruhrgas
         actual or contingent, conditional or unconditional, due or not due,
         present or future capable of being accounted or provided for in annual
         accounts related to causes that have accrued prior to the Effective
         Date other than those liabilities (i) disclosed or provided for in the
         Accounts; (ii) incurred in the ordinary course of business since the
         Balance Sheet Date; or (iii) disclosed elsewhere in this PA or the
         Disclosure Letter.

8        LICENCES, AUTHORISATIONS AND CONSENTS
         All material licences, consents, authorisations, orders, warrants,
         confirmations, permissions, certificates, approvals and authorities
         ("LICENCES") necessary for the carrying on of the businesses and
         operations of each of the Gelsenberg Group Companies and Ruhrgas as now
         carried on to the best of BP's knowledge have been obtained, are not
         limited in duration (except as provided by law or customary for such
         Licenses), nor subject to onerous conditions, are in full force and
         effect and have been and are being complied with in all material
         respects. To the Best of BP's Knowledge there is no investigation,
         enquiry or proceeding outstanding or threatened in writing which is
         likely to result in the suspension, cancellation, modification or
         revocation of any of such Licences. To the Best of BP's Knowledge none
         of such Licences has been breached in any material respect or is likely
         to be suspended, cancelled, refused, materially modified or revoked
         (whether as a result of the entry into or completion of this PA or
         otherwise).

9        LITIGATION
9.1      Save as set out in the Disclosure Letter, to the Best of BP's Knowledge
         since the Balance Sheet Date no claim for damages or otherwise has been
         made against any Gelsenberg Group Company or Ruhrgas.

9.2      Save as set out in the Disclosure Letter, no Gelsenberg Group Company
         or Ruhrgas (or any person for whose acts or defaults any Gelsenberg
         Group Company or Ruhrgas may be vicariously liable) is involved whether
         as plaintiff or defendant or other party in any claim, legal action,
         proceeding, suit, litigation, prosecution, investigation, enquiry or
         arbitration of material importance (other than as plaintiff in the
         collection of debts arising in the ordinary course of its business none
         of which exceeds Euro 1,000,000 (Euro one million) and those for which
         provisions have been made in the annual accounts) and no such claim,
         legal action, proceeding, suit, litigation, prosecution, investigation,
         enquiry or arbitration of material importance is pending or threatened
         in writing by or against any Gelsenberg Group Company or Ruhrgas (or
         any person for whose acts or defaults a Gelsenberg Group Company or
         Ruhrgas may be vicariously liable).

10       RUHRGAS
         BP's warranties under Clauses 5 to 9 (inclusive) in this Schedule 1 in
         relation to Ruhrgas are given subject to the qualification of the Best
         of BP's Knowledge.





                                      -16-
<PAGE>

      SCHEDULE 2 - RESERVED MATTERS OF THE SUPERVISORY BOARD OF GELSENBERG

1        The Managing Board needs the consent of the Supervisory Board to
         conclude transactions which are of special economic importance for the
         company. Such transactions are in particular:

1.1      Incorporation of enterprises, acquisition and sale of enterprises and
         of participations in other enterprises if the value exceeds Euro
         10,000,000 (Euro ten million) in any particular case.

1.2      Acquisition, creation and sale of fixed assets (e.g. buildings,
         movables, real property) if the value exceeds Euro 10,000,000 (Euro
         ten million) in any particular case.

1.3      Taking and letting on lease of real property and equivalent rights as
         well as creation of hereditary building rights if the cash value
         exceeds Euro 10,000,000 (Euro ten million) in any particular case.

1.4      The following transactions:

         (a)      issuance of bonds and similar securities

         (b)      capital increase and participation in capital increase (except
                  in the case of wholly owned domestic direct or indirect group
                  companies) if the value (Gelsenberg share) exceeds Euro
                  10,000,000 (Euro ten million) in any particular case.

1.5      Granting general powers of attorney or "prokura" as well as appointment
         of directors.

1.6      Material and extensive changes in the organisational structure and
         important measures with respect to employment policy within Gelsenberg
         and in such subsidiaries which do not have their own supervisory board
         statutory employees' representation.

2        The consent shall always be obtained in advance. In urgent cases prior
         consent of the chairman of the Supervisory Board shall be sufficient;
         the transaction shall subsequently be presented to the Supervisory
         Board for approval.

3        In view of the character of Gelsenberg as a strategic financial holding
         the following shall apply with respect to the obligatory consent to
         transactions on the level of subsidiaries and holding companies:

         The provisions of items 1.1 to 1.3 above shall always be applied, even
         if the relevant transactions are concluded by subsidiaries or holding
         companies. With respect to investments this means that any investments
         of such companies with a value exceeding Euro 10,000,000 (Euro ten
         million) in any particular case require the consent of the Supervisory
         Board. If such companies are companies whose shares are not exclusively
         held by Gelsenberg such obligation of consent shall apply if the share
         in the transaction which is -- directly or indirectly -- attributed to
         Gelsenberg exceeds Euro 10,000,000 (Euro ten million).





                                      -17-
<PAGE>



               SCHEDULE 3 - BASIC TERMS OF SHAREHOLDERS AGREEMENT

1        No transfer, encumbrance or other disposition of shares in Gelsenberg
         unless other party consents in writing.

2        Financing: Gelsenberg to finance itself by use of third party debt if
         required.

3        BP will agree to participate pro rata to its share of Gelsenberg's
         capital in any capital increase or shareholder loans to Gelsenberg
         after 31 October 2003 up to a maximum of Euro 1 billion (Euro one
         billion) for BP's share and will vote for any shareholder resolutions
         required for such increases of capital. Any cash proceeds of such
         capital increases or shareholder loans may be freely applied by
         Gelsenberg including in the making of loans to E.ON. BP agrees and
         procures that Deutsche BP will agree to the conversion of Gelsenberg
         into a GmbH if requested to do so by E.ON on or after April 1, 2002
         (but not before the Effective Date) and to change the Articles of
         Association of Gelsenberg to provide for the minimum shareholder rights
         for Deutsche BP required by law for a 49% shareholder (including those
         set out in Schedule 2 above).

4        RESERVED MATTERS:

4.1      BP and E.ON agree that they both shall make best efforts to ensure - to
         the extent legally permissible - that the matters listed in Schedule 2,
         supra, only are undertaken or executed by Gelsenberg if both, BP and
         E.ON, agree to such acts, transactions or the like.

4.2      E.ON undertakes, on request of BP, to vote in a shareholders meeting in
         favour of an amendment of the Articles of Association of Gelsenberg by
         which the undertaking and execution of certain or all of the reserved
         matters as provided in Schedule 2, supra, by the management board of
         Gelsenberg are made subject to approval by the supervisory board of
         Gelsenberg in accordance with sect. 111 para 4., 2nd sentence, of the
         German Stock Corporation Law (Aktiengesetz).





                                      -18-
<PAGE>



                            SCHEDULE 4 - BP INDEMNITY



1        TAXES

1.1      TAX INDEMNITY
         BP shall hold E.ON and the Gelsenberg Group Companies fully harmless
         and indemnified from all taxes and ancillary tax duties as defined in
         Section 3 German General Tax Code (AO), social charges and other public
         dues of Gelsenberg (the "PUBLIC CHARGES"), if both of the following
         conditions are fulfilled:

         1.1.1    the Public Charges have accrued until the Effective Date; and

         1.1.2    the Public Charges have not been paid until the Effective
                  Date; and

         1.1.3    the Public Charges have not been reflected or provided for or
                  exceed the amounts at which they are reflected or provided for
                  in the latest Balance Sheets as of or prior to the Effective
                  Date of the Gelsenberg Group Companies prepared in accordance
                  with respective applicable local GAAP.

         If and to the extent additional Public Charges have to be paid due to
         audits of the respective authorities for the period prior to the
         Effective Date, the above obligation applies mutatis mutandis. If and
         to the extent such audit leads only to a rescheduling of Public
         Charges, resulting in subsequent years in a reduction of the burden
         with respect to such Public Charges, BP's liability to indemnify and
         hold harmless shall be restricted to compensate for interest losses
         caused by such rescheduling. The basis for the reductions of burdens
         shall be calculated separately on a stand-alone basis for the
         Gelsenberg Group Companies. If and to the extent that additional taxes
         are to be borne by Deutsche BP because of the existing taxwise
         integration of the Gelsenberg Group Companies into the Deutsche BP
         (steuerliche Organschaft), E.ON shall ensure that tax-reduction effects
         in favour of the Gelsenberg Group Companies are paid out to Deutsche BP
         as soon as corresponding tax refunds have been received or are deemed
         to have been received from the fiscal authorities by E.ON, E.ON Group
         Companies or Gelsenberg Group Companies and disregarding the existence
         of corporation tax losses or the use of corporation tax loss carry
         forwards.

         Indemnification claims pursuant to this provision shall become
         time-barred six months after all assessments for all Public Charges for
         periods prior to the Effective Date have become final (bestandskraftig)
         following all relevant audits of tax and other public authorities.

1.2      In determining indemnification amounts payable pursuant to Clauses 1.1,
         supra, the tax reducing or tax increasing effects, respectively, of
         such indemnification payments shall be taken into consideration.

2        HANDLING OF TAX MATTERS
         With respect to the handling of matters related to Public Charges,
         which relate to, or result from a tax audit covering the period prior
         to the Effective Date, the following shall apply:

         2.1.1    Any matters regarding Public Charges shall be handled by E.ON
                  and Gelsenberg in co-ordination with Deutsche BP. E.ON shall
                  notify Deutsche BP in due time of any such matter, in
                  particular of a tax audit relating to the period prior to the





                                      -19-
<PAGE>


                  Effective Date. Deutsche BP shall be entitled to participate
                  in any such matter and to comment thereon. Any binding
                  declaration vis-a-vis public authorities relating to the
                  period prior to the Effective Date shall only be made if
                  Deutsche BP has given its prior consent, such consent not to
                  be unreasonably withheld.

         2.1.2    E.ON and Gelsenberg shall grant full access to Deutsche BP and
                  its representatives to all books and records of Gelsenberg
                  during regular business hours, to the extent this is necessary
                  to fend off claims regarding Public Charges asserted by public
                  authorities for periods prior to the Effective Date.

         2.1.3    Upon Deutsche BP's instruction and at its cost Gelsenberg
                  shall take up any remedy in connection with the foregoing in
                  co-ordination with Deutsche BP.


















                                      -20-