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                                                                 EXHIBIT 4.26







                              AMENDED AND RESTATED
                             SHAREHOLDERS AGREEMENT

                                  by and among

                                360NETWORKS INC.

                                     DWF SRL

                          GS CAPITAL PARTNERS III, L.P.

                            GSCP3 WWF (BARBADOS) SRL

                               WWF (BARBADOS) SRL

                          PROVIDENCE EQUITY FIBER, L.P.

                               TYCO GROUP S.A.R.L.

                          WORLDWIDE FIBER HOLDINGS LTD.

                                   LEDCOR INC.

                                       and

                  THE SEVERAL SHAREHOLDERS NAMED IN SCHEDULE I



                                   dated as of

                                 April 20, 2000




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                                TABLE OF CONTENTS

<TABLE>
<CAPTION>


<S>     <C>                                                                                                      <C>
SECTION 1. Certain Definitions....................................................................................2
SECTION 2. Methodology for Calculations...........................................................................4
SECTION 3. Corporate Governance...................................................................................4
         3.1      Board of Directors..............................................................................4
         3.2      Vacancies; Removal..............................................................................5
         3.3      Quorum..........................................................................................5
         3.4      Directors' Indemnification......................................................................6
         3.5      No Expansion of Duties..........................................................................6
         3.6      Expenses.  .....................................................................................7
         3.7      Appointment of Senior Officers..................................................................7
         3.8      Shareholder Voting Arrangement..................................................................7
SECTION 4. Representations and Warranties.........................................................................8
SECTION 5. Certain Covenants......................................................................................9
         5.1      Protection of Investors.........................................................................9
         5.2      System of Accounting............................................................................9
         5.3      Compliance with Laws............................................................................9
         5.4      Insurance.......................................................................................9
         5.5      Licenses and Permits............................................................................9
         5.6      Disclosure of Investment........................................................................9
SECTION 6. Confidentiality.......................................................................................10
SECTION 7. Specific Performance; Injunction......................................................................11
SECTION 8. No Inconsistent Agreements.  .........................................................................11
SECTION 9. Further Assurances.  .................................................................................12
SECTION 10. Contractual Management Rights........................................................................12
SECTION 11. Severability.........................................................................................12
SECTION 12. Governing Law; Waiver of Jury Trial..................................................................12
SECTION 13. Condition to Effectiveness; Successors and Assigns...................................................13
SECTION 15. Amendments...........................................................................................17
SECTION 16. Headings.............................................................................................17
SECTION 17. Nouns and Pronouns...................................................................................17
SECTION 18. Entire Agreement.....................................................................................18
SECTION 19. Counterparts.........................................................................................18
SECTION 20. No Partnership.......................................................................................18
SECTION 21. Ledcor Assurances....................................................................................18
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                              AMENDED AND RESTATED
                             SHAREHOLDERS AGREEMENT

          This AMENDED AND RESTATED SHAREHOLDERS AGREEMENT (the "Agreement"),
dated as of April 20, 2000, by and among 360NETWORKS INC. (formerly called
WORLDWIDE FIBER INC.), a corporation continued under the laws of Nova Scotia
(the "Corporation"), DWF SRL, a Barbados company ("DLJ"), GS CAPITAL PARTNERS
III, L.P., a Delaware limited partnership ("GSCP") (signatory hereto solely for
purposes of Section 3), GSCP3 WWF (Barbados) SRL, a Barbados company, WWF
(Barbados) SRL, a Barbados company, each of which is an affiliate of The Goldman
Sachs Group, Inc. (collectively, with GSCP, the "GSCP Parties"), PROVIDENCE
EQUITY FIBER, L.P., a Delaware limited partnership, ("Providence"), TYCO GROUP
S.a.r.l., a Luxembourg corporation ("Tyco") (collectively with DLJ, the GSCP
Parties and Providence, the "Investors") WORLDWIDE FIBER HOLDINGS LTD., an
Alberta corporation ("WFH"), LEDCOR INC., an Alberta corporation ("Ledcor")
(signatory hereto solely for purposes of the Sections specified in Section 21),
and the signatories listed on Schedule I hereto.

                              W I T N E S S E T H :

          WHEREAS, the parties hereto are parties to that certain Shareholders
Agreement, dated as of September 9, 1999 as amended by that certain Amending and
Waiver Agreement dated December 22, 1999, that certain Joinder to the
Shareholders Agreement dated as of March 6, 2000 and that certain Second
Amending Agreement dated as of March 9, 2000 (the "Prior Shareholders
Agreement").

          WHEREAS, the Corporation and the Investors are parties to that certain
Preferred Share Purchase Agreement, dated as of September 7, 1999 as
supplemented by the Amending and Waiver Agreement dated December 22, 1999 and
the Adjustment of Shares Agreement dated March 6, 2000 (the "Purchase
Agreement"), pursuant to which the Corporation has issued to the Investors, and
the Investors have purchased from the Corporation, shares of a series of
Preferred Shares (the "Series A Non-Voting Preferred Shares").

          WHEREAS, the Corporation is contemplating a public offering pursuant
to the prospectus dated April 19, 2000 (the "Public Equity Offering") and the
parties hereto desire immediately upon the consummation of that public offering
to amend and restate the Shareholders Agreement in its entirety to establish and
set forth their agreement with respect to certain rights and obligations
associated with ownership of Shares (as defined below).


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          NOW, THEREFORE, in consideration of the premises and the mutual
covenants and obligations hereinafter set forth, the parties hereto hereby agree
as follows:


          SECTION 1. Certain Definitions. As used herein, the following terms
shall have the following meanings (capitalized terms used herein and not
otherwise defined herein shall have the meanings assigned to such terms in the
Purchase Agreement):

          "Affiliate" shall mean (i) with respect to any Person, any other
Person directly or indirectly controlling or controlled by or under direct or
indirect common control with such specified Person, or (ii) with respect to any
individual, shall also mean the spouse, child (including a stepchild or an
adopted child), grandchildren, parent, brother, sister or other BONA FIDE estate
planning recipient thereof or any spouse of any of the foregoing, and each trust
created for the exclusive benefit of any one or more of them. Notwithstanding
the foregoing, neither the Corporation nor any Person controlled by the
Corporation shall be deemed to be an Affiliate of any Shareholder for purposes
of this Agreement.

          "Board" shall mean the Board of Directors of the Corporation.

          "Closing" means the closing of the Public Equity Offering.

          "Common Share Equivalents" shall mean all options, warrants and other
securities and obligations convertible into, or exchangeable or exercisable for,
at any time or upon the occurrence of any event or contingency and without
regard to any vesting or other conditions to which such securities may be
subject, Common Shares.

          "Common Shares" shall mean any common shares of the Corporation of any
class or series whether now or hereafter authorized, including without
limitation the Corporation's Subordinate Voting Shares and Multiple Voting
Shares and any shares into which such common shares may be exchanged,
reclassified, recapitalized, converted or otherwise.

          "Financial Investors" shall mean each of (i) DLJ, (ii) the GSCP
Parties and (iii) Providence, collectively.

          "In-The-Money Common Share Equivalents" shall mean, at any time, any
Common Share Equivalents as to which the effective price per Common Share
issuable upon conversion, exchange or exercise of such Common Share Equivalents
(determined by dividing (A) the sum of (x) the aggregate purchase price paid in
respect of such Common Share Equivalents plus (y) the aggregate amount payable
upon conversion, exchange or exercise of such Common Share Equivalents in order
to issue all Common


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Shares issuable pursuant to such Common Share Equivalents by (B) the number of
Common Shares issuable upon the conversion, exchange or exercise of such Common
Share Equivalents) is equal to or less than the then fair market value per
Common Share as determined in good faith by the Board.

          "Ledcor" shall mean Ledcor Inc., a corporation incorporated under the
laws of Alberta.

          "Ledcor Entities" shall mean Ledcor Inc. and each of its Subsidiaries,
collectively, except for those entities which are defined as WFI Entities in the
Purchase Agreement.

          "Person" shall mean any individual, corporation, limited liability
company, limited or general partnership, joint venture, association, joint-stock
company, trust, unincorporated organization, other entity or government or any
agency or political subdivisions thereof.

          "Sell" shall mean, as to any Shares, to sell, or in any other way
directly or indirectly transfer, assign, distribute, pledge, encumber or
otherwise dispose of, either voluntarily or involuntarily, including the
assignment or transfer of voting rights attaching to such Shares (if any); the
terms Sale, Selling and Sold shall have meanings correlative to the foregoing.

          "Senior Officer" shall mean any of the individuals, numbering at least
five, who hold any of the following positions or their functional equivalents
irrespective of actual title held in the Corporation: (A) Chairman; (B)
Vice-Chairman; (C) Chief Executive Officer; (D) President; (E) Chief Financial
Officer; (F) Chief Operating Officer; and (G) Executive Vice President.

          "Shareholders" shall mean the parties to this Agreement (other than
the Corporation, GSCP or, except as specified in Section 21, Ledcor) and any
other Person who executes, and agrees to be bound by the terms of, this
Agreement.

          "Shares" shall mean (i) any Common Shares and (ii) any Common Share
Equivalents, in each case, whether owned or outstanding on the date hereof or
hereafter.

          "Subsidiary" shall mean with respect to any Person, any company,
partnership or other entity (i) of which at least a majority of the shares of
capital stock or other ownership interests having ordinary voting power to elect
a majority of the board of directors or other similar managing body of such
company, partnership or other entity are at the time owned or controlled,
directly or indirectly, by such Person or (ii) the management of which is
otherwise controlled, directly or indirectly, through one or more intermediaries
by such Person.


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          SECTION 2. Methodology for Calculations. For purposes of this
Agreement, the Sale of a Common Share Equivalent (whether or not an In-The-Money
Common Share Equivalent) shall be treated as the Sale of the Common Shares into
which such Common Share Equivalent can be converted, exchanged or exercised.
Except as otherwise specifically provided in this Agreement, for purposes of all
calculations under this Agreement (including, without limitation, calculations
to determine the ownership of Common Shares of any Shareholder and the
percentage of outstanding Common Shares owned by any Shareholder), (without
duplication) all In-The-Money Common Share Equivalents, but no other Common
Share Equivalents, shall be treated as having been converted, exchanged or
exercised into or for Common Shares.

          SECTION 3. Corporate Governance.

          3.1    Board of Directors.

          (a) The Board shall have overall responsibility for managing and
supervising the management of the business and affairs of the Corporation, and
the power and authority of the directors shall be subject only to such
restrictions as are imposed by this Agreement and by applicable law.

          (b) The maximum number of members of the Board shall be seventeen
(17).

          (c) From and after the date hereof and until DLJ, together with its
Investor Affiliates, Sell 25% or more of the Shares issued to it pursuant to the
Purchase Agreement (as equitably adjusted to reflect any stock split, stock
dividend, combination, reorganization, recapitalization, reclassification or
other similar event involving Common Shares), DLJ shall have the right to
nominate one person (the "DLJ Nominee") to serve as a director on the Board.

          (d) From and after the date hereof and until the GSCP Parties,
together with their Investor Affiliates, Sell 25% or more of its Shares issued
to it pursuant to the Purchase Agreement (as equitably adjusted to reflect any
stock split, stock dividend, combination, reorganization, recapitalization,
reclassification or other similar event involving Common Shares), GSCP shall
have the right to nominate one person (the "GSCP Nominee") to serve as a
director on the Board.

          (e) From and after the date hereof and until Providence, together with
its Investor Affiliates, Sell 25% or more of the Shares issued to it pursuant to
the Purchase Agreement (as equitably adjusted to reflect any stock split, stock
dividend, combination, reorganization, recapitalization, reclassification or
other similar event involving Common


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Shares), Providence shall have the right to nominate one person (the "Providence
Nominee") to serve as a director on the Board.

          (f) From and after the date hereof and until Tyco, together with its
Investor Affiliates, Sell 56% or more of the Shares issued to it pursuant to the
Purchase Agreement (as equitably adjusted to reflect any stock split, stock
dividend, combination, reorganization, recapitalization, reclassification or
other similar event involving Common Shares), Tyco shall have the right to
nominate one person (the "Tyco Nominee"; collectively with the DLJ Nominee, the
GSCP Nominee and the Providence Nominee, the "Investor Nominees"), to serve as a
director on the Board.

          (g) From and after the date hereof, the remaining members of the Board
(the "Non-Investor Nominees", collectively with the DLJ Nominee, the GSCP
Nominee, the Providence Nominee and the Tyco Nominee, the "Nominees") shall be
nominated by members of management of the Corporation provided that so long as
Gregory B. Maffei (the "Executive") is employed as chief executive officer of
the Corporation, three of such nominees shall be nominated by the Executive,
subject to reasonable approval of the majority of the then members of the board,
and the balance of such nominees shall be nominated by WFH.

          (h) At each meeting of Shareholders at which the election of members
of the Board is on the agenda, the Corporation shall recommend to Shareholders
the election of the Nominees as directors.

          3.2   Vacancies; Removal.

          (a) Subject to paragraph (b) of this Section 3.2, each director of the
Corporation shall hold office until his or her death or resignation or until his
or her successor shall have been duly elected and qualified. If any Investor
Nominee shall cease to serve as a director of the Corporation for any reason,
the vacancy resulting thereby shall be filled by another director nominated by
the Investor initially nominating that director.

          (b) Each Investor, shall have the right to call a meeting of
Shareholders to put forward a resolution of the Shareholders removing any
director designated by it, with or without cause, at any time.

          3.3    Quorum.

          (a) Subject to paragraphs (b) and (c) below, a quorum for meetings of
the Board shall be (i) in the case of notice of at least 48 hours before the
time fixed for the meeting, a majority of the directors then in office and (ii)
in the case of notice of at least


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24 hours but less than 48 hours before the time fixed for the meeting, the
number of directors then in office less three (3).

          (b) If at a meeting of directors a quorum is not present, the
directors present at such meeting may adjourn the meeting to a fixed time and
place (provided they shall give written notice of such time and place to each
director not in attendance). At the meeting immediately following the adjourned
meeting, the directors present at such meeting shall constitute a quorum;
provided, however, that unless a full quorum is present as provided in paragraph
(a) above, the directors present at such meeting may not transact any business
except as specifically set forth in the notice of meeting.

          (c) The Corporation agrees that (i) each director shall be provided
written notice of the meetings of the Board , including adjourned meetings, at
least twenty-four (24) hours before such meetings, unless such notice is waived
in any manner, with attendance at such meetings constituting valid waiver (other
than attendance for the express purpose of objecting to the manner in which the
meeting was called), and (ii) each director shall be provided with an
opportunity to participate in each meeting of the Board by means of a conference
telephone or similar communications equipment.

          3.4    Directors' Indemnification.

          (a) The Corporation shall obtain and cause to be maintained in effect,
with financially sound insurers, a policy of directors' and officers' liability
insurance in an amount of at least US$5,000,000 or more and upon such terms as
are reasonably acceptable to the Investors.

          (b) The Memorandum of Association and Articles of Association or both,
shall to the fullest extent permitted by law provide for indemnification of, and
advancement of expenses to, and limitation of the personal liability of, the
directors of the Corporation or such other person or persons, if any, who,
pursuant to a provision of such Articles of Incorporation, exercise or perform
any of the powers or duties otherwise conferred or imposed upon such directors,
which provisions shall not be amended, repealed or otherwise modified in any
manner adverse to the directors until at least six (6) years following the date
that the Investors are no longer entitled to designate directors pursuant to
this Section 3.

          3.5 No Expansion of Duties. The parties acknowledge that the Financial
Investors, their Investor Affiliates and Canadian National Railway Company
("CN") and CN's Affiliates have investments in other business similar to and
which may compete with the Corporation's businesses ("Competing Businesses") and
reserve the right to make additional investments in other Competing Businesses
independent of their investments in the Corporation. By virtue of a Financial
Investor or CN holding Shares


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or by having persons designated by or affiliated with such person serving on the
Board or any Subsidiary's Board of Directors (or the functional equivalent
thereof in the case of non-corporate Subsidiaries) or otherwise, no Financial
Investor, any of the Investor Affiliates, CN nor CN's Affiliates shall have any
obligation to the Corporation, any Subsidiary or any holder of Shares to refrain
from competing with the Corporation or any Subsidiary, making investments in
Competing Businesses, otherwise engaging in any commercial activity, and none of
the Corporation, any Subsidiary or any holder of Shares (other than such person)
shall have any right with respect to any such investments or activities
undertaken by such Financial Investor or CN. Without limitation of the
foregoing, each Financial Investor, any Investor Affiliates, CN or CN's
Affiliates may engage in or possess an interest in other business ventures of
any nature or description, independently or with others, similar or dissimilar
to the business of the Corporation or any Subsidiary, and none of the
Corporation, any Subsidiary or any holder of Shares (other than the person)
shall have any rights or expectancy by virtue of such person's relationships
with the Corporation, any Subsidiary, this Agreement or otherwise in and to such
independent ventures or the income of profits derived therefrom; and the pursuit
of any such venture, even if such investment is in a Competing Business, shall
not be deemed wrongful or improper. No Financial Investor, any Investor
Affiliates, CN nor CN's Affiliates shall be obligated to present any particular
investment opportunity to the Corporation or any Subsidiary even if such
opportunity is of a character that, if presented to the Corporation or a
Subsidiary, could be taken by the Corporation or such Subsidiary, and the
Financial Investor, their Investor Affiliates, CN or CN's Affiliates shall
continue to have the right to take for their own respective account or to
recommend to others any such particular investment opportunity.

          3.6 Expenses. The Corporation shall pay all reasonable travel expenses
and other out-of-pocket disbursements incurred by the directors to attend
meetings of the Board, of any Subsidiary board of directors or of any committees
thereof.

          3.7 Appointment of Senior Officers. The Board shall have the sole and
absolute authority to elect, appoint or hire any Senior Officer of the
Corporation.

          3.8 Shareholder Voting Arrangement. Each Shareholder, other than DLJ
and the GSCP Parties, agrees to vote all Voting Shares of the Corporation
beneficially owned by it with respect to the election or removal, to or from the
Board, of (a) so long as Providence has the right to nominate a Providence
Nominee in accordance with Section 3.1(e), the Providence Nominee in accordance
with the directions of Providence, (b) so long as Tyco has the right to nominate
a Tyco Nominee in accordance with Section 3.1(f), the Tyco Nominee in accordance
with the directions of Tyco, and (c) the Non-Investor Nominees in accordance
with the directions of the Person or Persons entitled to nominate such Nominees
in accordance with Section 3.1(g).


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          SECTION 4. Representations and Warranties

          (a) Each of the parties hereto represents and warrants to the other
parties hereto as follows:

              (i) It has full power and authority to execute, deliver and
perform its obligations under this Agreement;


              (ii) This Agreement has been duly and validly authorized, executed
and delivered by it, and constitutes a valid and binding obligation of it,
enforceable against it in accordance with its terms except to the extent that
enforceability may be limited by bankruptcy, insolvency or other similar laws
affecting creditors' rights generally;

              (iii) The execution, delivery and performance of this Agreement by
it does not (A) violate, conflict with, or constitute a breach of or default
under its organizational documents, if any, or any material agreement to which
it is a party or by which it is bound or (B) violate any law, regulation, order,
writ, judgment, injunction or decree applicable to it;

              (iv) No consent or approval of, or filing with, any governmental
or regulatory body is required to be obtained or made by it in connection with
the transactions contemplated hereby (except those which have been made or
obtained); and

              (v) It is not a party to any contract or agreement which is
inconsistent with the rights of any party hereunder or otherwise conflicts with
the provisions hereof.

          (b) The Corporation represents and warrants to each of the Investors
and the Investor Affiliates as follows:

              (i) The disclosure contained in the Corporation's prospectus dated
April 19, 2000 under the captions "Description of Our Capital Stock",
"Capitalization", and "Description of Capital Stock and Share Capital
Reorganization" are true and complete in all material respects;

              (ii) the transactions contemplated by the Ledcor Roll-up Agreement
(as defined in the Prior Shareholders Agreement) have occurred in accordance
with its terms; and

              (iii) the Minority Roll-Up Transactions (as defined in the Prior
Shareholders Agreement) have each occurred or will occur immediately prior to
the


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closing of the Public Equity Offering in accordance with the Minority Roll-Up
Agreements (or other transactions or series of transactions with similar
effect).

          (c) Ledcor represents and warrants to each of the parties hereto that
Ledcor did not breach Section 12.16 of the Prior Shareholders Agreement.

          SECTION 5. Certain Covenants.

          5.1 Protection of Investors. The Corporation and the Shareholders each
agree that all of the following provisions of this Section 5 are for the
exclusive benefit, protection and enjoyment of each of the Investors (severally
and not jointly) and their permitted successors and assigns, and may only be
enforced or remedied by the Investors (severally and not jointly) and their
permitted successors and assigns.

          5.2 System of Accounting. The books of account and other financial and
corporate records of the Corporation and its Subsidiaries shall be maintained in
accordance with good business and accounting practices and the financial
condition of the Corporation shall be accurately reflected in the financial
statements referred to in this Section.

          5.3 Compliance with Laws. The Corporation shall, and shall cause each
of its Subsidiaries to, comply with all applicable laws, rules regulations and
orders except where failure to comply would not have a material adverse effect.

          5.4 Insurance. The Corporation shall, and shall cause each of its
Subsidiaries to, keep its assets and those of its Subsidiaries which are of an
insurable character, if any, insured by financially sound and reputable insurers
against loss or damage by fire, extended coverage and other hazards and risks
and liability to Persons and property to the extent and in the manner customary
for companies in similar businesses similarly situated.

          5.5 Licenses and Permits. The Corporation shall, and shall cause each
of its Subsidiaries to, use its best efforts to obtain all Canadian and
non-Canadian federal, provincial, state and local governmental licenses,
permits, authorizations, consents, waivers, certificates and approvals material
to and necessary in the conduct of their business, including the Hibernia
Project.

          5.6 Disclosure of Investment. The Corporation, on the one hand, and
each of the Investors, on the other hand, agrees that it will not use in
advertising or publicity the name of any party hereto, or any partner or
employee of such party hereto or any of its respective affiliates, or any trade
name, trademark, trade device, service mark, symbol or any abbreviation,
contraction or simulation thereof owned by the other party hereto or any of its
respective affiliates, in either case without the prior written consent of


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such party (except as such release or announcement may be required by applicable
securities law or the rules or regulations of the United States Securities and
Exchange Commission, in which case the party required to make the release or
announcement shall make reasonable best efforts to allow each other party
reasonable time to comment on such release or announcement in advance of such
issuance). From and after the date hereof, neither the Corporation nor any of
its Subsidiaries will represent, directly or indirectly, that any product or any
service provided by the Corporation has been approved or endorsed by any
Investor without the prior written consent of all of the Investors. The
Corporation and each of the Investors further agree that, from the date hereof
through the Closing Date, no public release or announcement concerning the
transactions contemplated hereby shall be issued by any party without the prior
consent of the Corporation and each Investor (which consent shall not be
unreasonably withheld), except as such release or announcement may be required
by applicable securities law or the rules or regulations of the United States
Securities and Exchange Commission, in which case the party required to make the
release or announcement shall make reasonable best efforts to allow each other
party reasonable time to comment on such release or announcement in advance of
such issuance.

          SECTION 6. Confidentiality.

          (a) The Investors and each of the other Shareholders severally (the
"Confidants") recognize that certain non-public, confidential, proprietary
information ("Confidential Information") may be furnished orally or in writing
to the Confidants by, or at the direction of, the Corporation. The Confidants
agree not to disclose any Confidential Information to any Person except to a
Person who is advised of the Confidant's obligations under this Section 6 and
who is (i) a partner, managing director, director, officer or employee of a
Confidant or a Confidant's Affiliate who is involved in the Confidant's
investment in the Corporation, who is consulted with respect to such investment,
or who a Confidant determines otherwise needs to know such information, or (ii)
a Person acting as an advisor to a Confidant in connection with such investment,
except with the consent of the Corporation or pursuant to a subpoena, civil
investigative demand (or similar process), order, statute, rule or other legal
requirement promulgated or imposed by a court or by a judicial, regulatory,
self-regulatory or legislative body, organization, agency or committee or
otherwise in connection with any judicial or administrative proceeding
(including, in response to oral questions, interrogatories or requests for
information or documents) in which a Confidant or Investor Affiliate is
involved. The Confidants acknowledge that the United States securities laws
prohibit any person who is in possession of material, non-public information
regarding an issuer from purchasing or selling securities of such issuer or from
communicating such information to any other person under circumstances in which
it is reasonably foreseeable that such person is likely to purchase or sell such
securities.


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<PAGE>


          (b) If Confidential Information is to be disclosed pursuant to the
foregoing paragraph, the Confidant will, to the extent practicable, promptly
notify the Corporation thereof and cooperate with the Corporation to the extent
legally permissible if it should seek to obtain an order or other reliable
assurance that confidential treatment will be accorded to designated portions of
the Confidential Information. The Confidants shall be entitled to periodic
reimbursement from the Corporation for expenses incurred by it or any Investor
Affiliate, including the fees and expenses of counsel, in connection with any
action taken pursuant to this paragraph.

          (c) Information will not be deemed Confidential Information if it (i)
was already available to, or in the possession of, the Confidant prior to its
disclosure by, or at the direction of, the Corporation, (ii) is or becomes
available in the public domain on or after the date hereof (other than as a
result of a disclosure by any Confidant or any of its advisors), or (iii) is
acquired from a person who is not known by a Confidant to be in breach of an
obligation of confidentiality to the Corporation.

          SECTION 7. Specific Performance; Injunction.

          (a) The parties agree that it is impossible to determine the monetary
damages which would accrue to the Corporation or any Shareholder or his personal
representative by reason of the failure of any Other Shareholder or the
Corporation to perform any of his or its obligations under this Agreement
requiring the performance of an act other than the payment of money only. Each
Shareholder shall be entitled to enforce its rights under this Agreement
specifically and to exercise all other rights existing in their favor. The
parties hereto agree and acknowledge that money damages may not be an adequate
remedy for any breach of the provisions of this Agreement and that each party
may in its sole discretion apply to any court of law or equity of competent
jurisdiction for specific performance and/or injunctive relief (without posting
a bond or other security) in order to enforce or prevent any violation of the
provisions of this Agreement.

          (b) In the event of a breach or threatened breach by a Shareholder of
any of the provisions of this Agreement, the Corporation, and the remaining
Shareholders shall be entitled to an injunction restraining such Shareholder
from any such breach. The availability of these remedies shall not prohibit the
Corporation from pursuing any other remedies for such breach or threatened
breach, including the recovery of damages from the Shareholder.

          SECTION 8. No Inconsistent Agreements. Neither the Corporation nor any
Shareholder shall take any action or enter into any agreement which is
inconsistent with the rights of any party hereunder or otherwise conflicts with
the provisions hereof.


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          SECTION 9. Further Assurances. At any time or from time to time after
the date hereof, the parties agree to cooperate with each other, and at the
request of any other party, to execute and deliver any further instruments or
documents and to take all such further action as the other party may reasonably
request in order to evidence or effectuate the consummation of the transactions
contemplated hereby and to otherwise carry out the intent of the parties
hereunder.

          SECTION 10. Contractual Management Rights. The Corporation and each of
the Shareholders acknowledge that the provisions of this Agreement are intended,
among other things, to provide DLJ, GSCP and Providence with "contractual
management rights" within the meaning of the Employee Retirement Income Security
Act of 1974, as amended, and the regulations promulgated thereunder.

          SECTION 11. Severability. Whenever possible, each provision of this
Agreement shall be interpreted in such manner as to be effective and valid, but
if any provision of this Agreement is held to be invalid or unenforceable in any
respect, such invalidity or unenforceability shall not render invalid or
unenforceable any other provision of this Agreement. In the event that pursuant
to any regulatory authority or regulation, the Corporation is required to make
any revisions or modifications to any provision of this Agreement or any of the
other Documents, the parties agree to enter into good faith negotiations and
make revisions or modifications, to the extent possible, that are in compliance
with such regulation or the rules of such regulatory authority, and which are
designed to accomplish the purposes of such provision to be revised or modified.

          SECTION 12. Governing Law; Waiver of Jury Trial. This Agreement shall
be governed by and construed in accordance with the laws of the State of New
York without giving effect to the principles of conflicts of law, except for the
provisions of Section 3, which shall be governed by and construed in accordance
with the laws of the Province of British Columbia and the federal law of Canada.
Each of the parties hereto hereby irrevocably and unconditionally consents to
submit to the exclusive jurisdiction of the courts of the State of New York and
of the United States of America, in each case located in the County of New York,
for any action, proceeding or investigation in any court or before any
governmental authority ("Litigation") arising out of or relating to this
Agreement and the transactions contemplated hereby (and agrees not to commence
any Litigation relating thereto except in such courts), and further agrees that
service of any process, summons, notice or document by facsimile or registered
mail to its respective address set forth in this Agreement shall be effective
service of process for any Litigation brought against it in any such court. Each
of the parties hereto hereby irrevocably and unconditionally waives any
objection to the laying of venue of any Litigation arising out of this Agreement
or the transactions contemplated hereby in the courts of the State of


                                     - 12 -
<PAGE>


New York and of the United States of America, in each case located in the County
of New York,, and hereby further irrevocably and unconditionally waives and
agrees not to plead or claim in any such court that any such Litigation brought
in any such court has been brought in an inconvenient forum. EACH OF THE PARTIES
IRREVOCABLY AND UNCONDITIONALLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY
APPLICABLE LAW, ANY AND ALL RIGHTS TO TRIAL BY JURY IN CONNECTION WITH ANY
LITIGATION ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS
CONTEMPLATED HEREBY.

          SECTION 13. Condition to Effectiveness; Successors and Assigns. This
Agreement shall only become effective upon the public Sale of equity securities
of the Company pursuant to a final prospectus (for which a receipt or receipts
have been obtained) no later than May 15, 2000. Until this Agreement becomes
effective (or if this Agreement never becomes effective) the parties hereto
agree that the Prior Shareholders Agreement will remain in full force and effect
without amendment or modification. This Agreement shall inure to the benefit of
and shall be binding upon the parties hereto and their respective successors,
assigns, heirs and personal representatives. No Shareholder shall have the right
to assign its rights under Section 3 of this Agreement without the consent of
the Corporation and each other Investor. Upon any such assignment, such assignee
shall have and be able to exercise all rights of the assigning Shareholder. The
parties acknowledge that, subject to compliance with applicable securities laws,
each Investor may transfer and assign all or a part of its rights and
obligations under this Agreement (including, for the avoidance of doubt, under
Section 3) to one or more other partnerships, corporations, trusts or other
organizations which have been created by or are controlled by, control or are
under common control with such Investor or one or more of the then current
partners, members or other equity holders of such Investor (the "Investor
Affiliates"), without the consent of the Corporation or any other Shareholder.
In addition each transferee from WFH and Ledcor Limited Partnership pursuant to
Section 3(a)(ii) of the Prior Shareholder's Agreement may transfer and assign
all or a part of its rights and obligations under this Agreement (including, for
the avoidance of doubt, under Section 3) to one or more partnerships,
corporations, trusts or other organizations which have been created by or
controlled by, control or are under common control with such transferee or one
or more of the then current partners, members or other equity holders of such
transferee, without the consent of the Corporation or any Shareholder.
Notwithstanding the foregoing, neither the Corporation nor any Person controlled
by the Corporation shall be deemed to be an Investor Affiliate of any Investor
for purposes of this Agreement. Upon any such assignment, the assignee shall
have and be able to exercise all rights of the assigning Shareholder.

          SECTION 14. Notices. All notices, requests, consents and other
communications hereunder to any party shall be deemed to be sufficient if
contained in a written instrument delivered in Person or by telecopy, nationally
recognized overnight


                                     - 13 -
<PAGE>


courier or first class registered or certified mail, return receipt requested,
postage prepaid, addressed to such party at the address set forth below or such
other address as may hereafter be designated in writing by such party to the
other parties:

          (a) if to the Corporation, to:

                   360networks Inc..
                   #1510-1066 West Hastings Street
                   Vancouver, British Columbia  V6E 3X1
                   Fax:  (604) 681-6822
                   Attention:  Secretary

                   with a copy to:

                   Farris, Vaughan, Wills & Murphy
                   2600 - 700 West Georgia Street
                   Vancouver, British Columbia  V7Y 1B3
                   Fax:  (604)  661-9349
                   Attention:  Cameron G. Belsher

                   and

                   Cahill Gordon & Reindel
                   Eighty Pine Street
                   New York, New York
                   U.S.A.  10005
                   Fax:  (212) 269-5420
                   Attention:  Roger Andrus

          (b) if to DLJ, to:

                   DWF SRL
                   Chancery House
                   High Street
                   Bridgetown, Barbados, West Indies

                   and

                   DWF SRL
                   c/o DLJ Merchant Banking Partners II, L.P.
                   277 Park Avenue
                   New York, New York  10172


                                     - 14 -
<PAGE>


                   Fax:  (212) 892-7272
                   Attention:  Andrew Rush

                   with a copy to:

                   Latham & Watkins
                   885 Third Avenue, Suite 1000
                   New York, New York 10022-4802
                   Fax:  (212) 751-4864
                   Attention:  Steven Della Rocca

          (c) if to any of the GSCP Parties, to:

                   c/o Ernst & Young Services Ltd.
                   P.O. Box 261
                   Bay Street
                   Bridgetown,
                   Barbados, West Indies
                   Fax:  (246) 426-9551
                   Attention:  Carol-Ann Smith

                   and

                   c/o GS Capital Partners III, L.P.
                   85 Broad Street
                   New York, New York  10004
                   Fax:  (212) 902-3000
                   Attention:  Robert R. Gheewalla

                   with a copy to:

                   Fried, Frank, Harris, Shriver & Jacobson
                   One New York Plaza
                   New York, New York  10004
                   Fax:  (212) 859-4000
                   Attention:  Stuart Z. Katz

                   and

                   GS Capital Partners III, L.P.
                   85 Broad Street
                   New York, New York  10004


                                     - 15 -
<PAGE>


                   Fax:  (212) 357-5505
                   Attention:  Ben Adler

          (d) if to Providence, to:

                   Providence Equity Fiber, L.P.
                   50 Kennedy Plaza
                   Providence, Rhode Island  02903
                   Fax:  (401) 751-1790
                   Attention:  Glenn M. Creamer

                   with a copy to:

                   Edwards & Angell, LLP
                   2800 BankBoston Plaza
                   Providence, Rhode Island  02903
                   Fax:  (401) 276-6602
                   Attention:  David K. Duffell

          (e) if to Tyco, to:

                   Tyco Group S.A.R.L.
                   2nd Floor
                   6, Avenue Emile Reuter
                   L-2420 Luxembourg
                   Fax:  352-464-350
                   Attention:  Managing Director

                   with a copy to:

                   Tyco Submarine System Ltd.
                   250 Industrial Way West
                   Eatontown, New Jersey  07724
                   Fax:  (732) 578-7803
                   Attention:  General Counsel

          (f) if to WFH, to:

                   Worldwide Fiber Holdings Ltd.
                   1000-1066 West Hastings Street
                   Vancouver, British Columbia  V6E 3X1
                   Fax:  (604) 681-6822
                   Attention:  Chief Financial Officer


                                     - 16 -
<PAGE>


                   with a copy to:

                   McLennan Ross
                   600 West Chambers
                   12220 Stony Plain Road
                   Edmonton, Alberta  T5N 3Y4
                   Fax:  (780) 482-9102
                   Attention:  Rodney R. Neys

          (g) if to Ledcor, to:

                   Ledcor Inc.
                   1000-1066 West Hastings Street
                   Vancouver, British Columbia  V6E 3X1
                   Fax:  (604) 681-6650
                   Attention:  David Lede

                   with a copy to:

                   McLennan Ross
                   600 West Chambers
                   12220 Stony Plain Road
                   Edmonton, Alberta  T5N 3Y4
                   Fax:  (780) 482-9102
                   Attention:  Rodney R. Neys

          (h) if to any other Shareholder, to the notice information set forth
in Schedule I hereto.

All such notices, requests, consents and other communications shall be deemed to
have been given when received.

          SECTION 15. Amendments. Unless otherwise set forth in this Agreement,
the terms and provisions of this Agreement may be modified or amended, or any of
the provisions hereof waived, temporarily or permanently, pursuant to the
written consent of the parties hereto.

          SECTION 16. Headings. The headings of the Sections of this Agreement
have been inserted for convenience of reference only and shall not be deemed to
be a part of this Agreement.

          SECTION 17. Nouns and Pronouns. Whenever the context requires, any
pronouns used herein shall include the corresponding masculine, feminine or
neuter


                                     - 17 -
<PAGE>

forms, and the singular form of names and pronouns shall include the plural and
vice-versa.


          SECTION 18. Entire Agreement. This Agreement and the other writings
referred to herein or delivered pursuant hereto which form a part hereof contain
the entire agreement among the parties hereto with respect to the subject matter
hereof and supersede all prior and contemporaneous agreements and understandings
with respect thereto.

          SECTION 19. Counterparts. This Agreement may be executed in any number
of counterparts, and each such counterpart shall be deemed to be an original
instrument, but all such counterparts together shall constitute but one
agreement.

          SECTION 20. No Partnership. The obligations of each of the parties to
this Agreement are several and not joint. Nothing in this Agreement shall imply
or be deemed to imply a partnership, joint venture or other relationship between
the parties.

          SECTION 21. Ledcor Assurances. On the date hereof, Ledcor is a direct
party to this Agreement for purposes of Sections 1, 4(c) and 6 through 21
(inclusive). Ledcor is also a direct party to this Agreement as a Shareholder
(as such) only if and so long as (whether now or at any time or from time to
time hereafter) it is a holder of Shares. Furthermore, Ledcor agrees to take all
action necessary to cause WFH or any other Affiliates of Ledcor (with the
exception of the Corporation and its Subsidiaries) to fully perform their
respective obligations under this Agreement.


                                     - 18 -
<PAGE>



          IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date first above written.

                                 360NETWORKS INC

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 DWF SRL

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 THE GSCP PARTIES:

                                 GS CAPITAL PARTNERS III, L.P.

                                 By: GS Advisors III, L.P., its general partner
                                 By: GS Advisors III, L.L.C., its general
                                     partner

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 GSCP3 WWF (Barbados) SRL

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:

                                 WWF (Barbados) SRL

                                 By: Signed
                                     ------------------------------------------
                                     Name:
                                     Title:


                                     - 19 -
<PAGE>



                                 PROVIDENCE EQUITY FIBER, L.P.

                                 By: Providence Equity Partners III L.P.
                                     its general partner,

                                 By: Providence Equity Partners III
                                     L.L.C.its general partner

                                 By: Signed
                                     -----------------------------------
                                     Name: Glenn M. Creamer
                                     Title:  Member and Managing
                                             Director

                                 TYCO GROUP S.A.R.L.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:

                                 WORLDWIDE FIBER HOLDINGS LTD.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:

                                 LEDCOR INC.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:

                                 CANADIAN NATIONAL RAILWAY
                                 COMPANY.

                                 By: Signed
                                     -----------------------------------
                                     Name:
                                     Title:


                                     - 20 -
<PAGE>


                                 Signed
                                 ----------------------------------------------
                                 CLIFFORD LEDE


                                 Signed
                                 ----------------------------------------------
                                 DAVID LEDE


                                 Signed
                                 ----------------------------------------------
                                 GREGORY B. MAFFEI


                                 Signed
                                 ----------------------------------------------
                                 LARRY OLSEN


                                 Signed
                                 ----------------------------------------------
                                 WILLIAM RAMSEY


                                 Signed
                                 ----------------------------------------------
                                 RON STEVENSON


                                 Signed
                                 ----------------------------------------------
                                 STEPHEN STOW


                                 Signed
                                 ----------------------------------------------
                                 JIM VOELKER



                                 MADISON SQUARE INC.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:



                                     - 21 -
<PAGE>



                                 LEDCOR INDUSTRIES LIMITED

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 LEDCOR INDUSTRIES LIMITED
                                 as General partner for Ledcor Partnership

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MACKENZIE PARTNERS, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:



                                     - 22 -
<PAGE>



                                 LIBERTY WF HOLDINGS LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 COMCAST TSIX HOLDINGS, INC.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 OAK INVESTMENTS PARTNERS IX, L.P.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 KLEINER PERKINS CAUFIELD & BYERS

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 InterNAP NETWORK SERVICES CORPORATION

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 NATHAN MYHRVOLD

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 divine interVentures, inc.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:



                                     - 23 -
<PAGE>



                                 GT GROUP TELECOM SERVICES CORP.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MSD SELECT SPONSORS VENTURES I, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 DBV INVESTMENTS, LP

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MSD EC I, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 BAYCLIFFE LIMITED

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 594745 B.C. LTD.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MACKENZIE PARTNERS II LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:



                                     - 24 -
<PAGE>


                                 NEWS AMERICA INCORPORATED

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:



                                     - 25 -
<PAGE>



                                 URBANLINK HOLDINGS LTD.

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 RAMSEY BEIRNE INVESTMENT
                                 PARTNERS, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:

                                 MI-TECH COMMUNICATIONS, LLC

                                 By: Signed
                                     -----------------------------------------
                                     Name:
                                     Title:



                                     - 26 -