<PAGE>

                                                                    EXHIBIT 10.6

                                                                  EXECUTION COPY

                      DATED the 17th day of September 2004

                      HUTCHISON INTERNATIONAL LIMITED                   (1)

                      HUTCHISON TELECOMMUNICATIONS
                      INTERNATIONAL (HK) LIMITED                        (2)

                            -------------------------

                            LOAN ASSIGNMENT AGREEMENT

                            -------------------------

<PAGE>

THIS LOAN ASSIGNMENT AGREEMENT is made the 17th day of September2004

BETWEEN

(1)  HUTCHISON INTERNATIONAL LIMITED, a company incorporated in Hong Kong whose
     registered office is at 22/F Hutchison House, 10 Harcourt Road, Hong Kong
     (the "Assignor"); and

(2)  HUTCHISON TELECOMMUNICATIONS INTERNATIONAL (HK) LIMITED, a company
     incorporated in Hong Kong whose registered office is at 22/F Hutchison
     House, 10 Harcourt Road, Hong Kong (the "Assignee").

WHEREAS:

(A)  Pursuant to a Sale and Purchase Agreement of even date hereof (the "Share
     Sale and Purchase Agreement"), HTI (BVI) Holdings Limited agreed to
     purchase, and Hutchison Telecommunications Limited agreed to sell, 1 share
     of US$1.00 in Hutchison Telecommunications (HK) Holdings Limited, which in
     turn holds interest in the group companies as set out in Schedule 2
     thereto.

(B)  Hutchison Telephone Company Limited is at 30 June 2004 indebted to the
     Assignor in the amount of HK$1,553,025,582.14 (the "Loan"), together with
     interest accrued in respect thereof.

(C)  The Loan is repayable on demand and interest on the Loan is charged at
     normal commercial rates as agreed between the Assignor and Hutchison
     Telephone Company Limited from time to time.

(D)  Subject to completion of the Share Sale and Purchase Agreement, the
     Assignee agreed to acquire from the Assignor, and the Assignor agreed to
     sell to the Assignee, all the benefit and interest of the Assignor in the
     Loan on the terms and subject to the conditions set out herein.

NOW THIS AGREEMENT WITNESSETH as follows:

1.   In consideration of the sum of HK$1,553,025,582.14 (receipt of which is
     hereby acknowledged by the Assignor), the Assignor as legal and beneficial
     owner hereby assigns unto the Assignee absolutely all its rights, title and
     interest in the Loan together with all rights attaching thereto (the
     "Assigned Rights") TO HOLD the same unto the Assignee absolutely. The
     Assignee hereby acquires the Assigned Rights absolutely.

<PAGE>

2.   The Assignor hereby warrants to the Assignee that:

     (a)  the Loan is repayable on demand and is still valid and subsisting and
          free from all claims, charges, liens, encumbrances, options, equities
          of any kind, compromise, releases, waivers, defects, and any agreement
          for any of the same; and

     (b)  the Assignor has the right, authority and power to assign its benefit
          of and in the Loan in the manner set out in this Agreement.

3.   The parties hereto acknowledge and confirm that as from the date hereof the
     Loan is owed to the Assignee, that the Assignee is entitled at any time and
     from time to time to require repayment of all or part of the same
     (including but without limitation interest accrued from time to time
     thereon) and that all payments due in respect of the Loan and all its
     obligations in respect thereof will be made and discharged directly to the
     Assignee.

4.   The Assignor hereby covenants with the Assignee to pay to the Assignee
     immediately on receipt any payments or other money which may be received by
     the Assignor from Hutchison Telephone Company Limited in respect of the
     Loan and until such payment to hold the same on trust for the Assignee.

5.   All payments made by the Assignee under Clause 1 of this Agreement shall be
     made gross, free of any rights of counterclaim or set-off and without any
     deductions or withholdings of any nature.

6.   Each party hereto undertakes to the other parties that it will do all such
     things and execute all such documents as may be necessary or desirable to
     carry into effect or to give legal effect to the provisions of this
     Agreement and the transactions hereby contemplated.

7.   Each party undertakes that it shall not reveal, and shall cause its
     shareholders, directors, senior executives, employees and agents not to
     reveal, to any third party any information concerning the transactions
     contemplated hereunder and/or the contents hereof (collectively,
     "Confidential Information") without the prior written approval of the other
     party hereto.

     Nothing in this Clause 7 shall prevent a party hereto from using or
     disclosing any Confidential Information which (a) is already known by such
     party at the time it is disclosed to it; (b) has been rightfully received
     by such party from a third party without a breach of an obligation of
     confidentiality; (c) is in the public domain through no wrongful act of
     such party; (d) is independently developed by such party without use,
     directly or indirectly, of the Confidential Information; (e) is required to
     be disclosed by applicable law, regulation or legal process or by judicial
     order; or (f) is in connection with the proposed spin off and listing of
     Hutchison Telecommunications International Limited.

<PAGE>

     Notwithstanding anything contained in this Agreement, each party
     acknowledges and agrees that the other party(ies) may be required by law or
     any competent regulatory body (including but without limitation to The
     Stock Exchange of Hong Kong Limited and the Securities and Futures
     Commission) to issue time sensitive and/or urgent announcements relating to
     this Agreement or matters contemplated under this Agreement. Each party
     shall procure to be provided to the other parties a copy of each drafts of
     such time sensitive and/or urgent announcements promptly, and shall
     consider in good faith any comments provided to it in a timely manner by
     the other parties to the extent reasonably practicable within the time
     frame stipulated by law or by the relevant competent regulatory body.

8.   Any notice required or permitted to be given by or under this Agreement
     shall be given in writing by delivering it to the party concerned to the
     address or facsimile number of that party below or such other address or
     facsimile number as the party concerned may have notified to the others in
     accordance with this Clause 8. Any such notice shall be deemed to be served
     if sent by hand at the time of delivery, or if sent by facsimile, on the
     date of complete transmission, or if sent by post, the third day after
     posting, or if sooner upon acknowledgement of receipt by or on behalf of
     the party to which it is addressed.

        Assignor:
        Address:     22nd Floor, Hutchison House, 10 Harcourt Road, Hong Kong
        Attention:   Company Secretary
        Fax No.:     (852) 2128 1778

        Assignee:
        Address:     22nd Floor, Hutchison House, 10 Harcourt Road, Hong Kong
        Attention:   Company Secretary
        Fax No.:     (852) 2128 1778

9.   This Agreement is governed by and shall be construed in accordance with the
     laws of the Hong Kong Special Administrative Region of the People's
     Republic of China ("Hong Kong") for the time being in force and the parties
     hereto hereby irrevocably submit to the non-exclusive jurisdiction of the
     Hong Kong courts in relation to any proceedings arising out of or in
     connection with this Agreement.

<PAGE>

IN WITNESS whereof this Loan Assignment Agreement has been duly signed on the
date first above written.

Signed by                                   )
Edith Shih                                  )
For and on behalf of                        )   /s/ Edith Shih
HUTCHISON INTERNATIONAL LIMITED             )   --------------------------------
was hereunto affixed in the presence of :   )


/s/ Patricia Hui
--------------------------------------


Signed by                                   )
Ting Chan                                   )
For and on behalf of                        )   /s/ Ting Chan
HUTCHISON TELECOMMUNICATIONS                )   --------------------------------
INTERNATIONAL (HK) LIMITED                  )
was hereunto affixed in the presence of :   )


/s/ Steven P. Allen
-------------------------------------