<PAGE>   1
                                                                     EXHIBIT 4.4

                          SECOND SUPPLEMENTAL INDENTURE

         SECOND SUPPLEMENTAL INDENTURE, dated as of June 15,1998, among (i) PLD
TELEKOM INC. (formerly known as Petersburg Long Distance Inc.), a Delaware
corporation (formerly an Ontario company, that became a Delaware corporation
pursuant to Section 388 of the General Corporation Law of the State of Delaware
pursuant to a Certificate of Domestication filed in Delaware on February 28,
1997) (the "Company"), as issuer, (ii) NWE CAPITAL (CYPRUS) LIMITED, a Cypriot
corporation ("NWE Cyprus"), PLD ASSET LEASING LIMITED, a Cypriot corporation
("PLD Leasing"), PLD CAPITAL LIMITED, a Cypriot corporation ("PLD Capital"), PLD
CAPITAL ASSET (U.S.) INC., a Delaware corporation ("PLD Capital Asset"),
WIRELESS TECHNOLOGY CORPORATIONS LIMITED, a British Virgin Islands corporation
("WTC"), and BALTIC COMMUNICATIONS LIMITED, a Russian joint stock company of the
closed type ("BCL"), as Guarantors, (iii) CLAYTON WAITE, shareholder of NWE
Cyprus as nominee of the Company, and APROPOS INVESTMENTS LTD., shareholder of
PLD Leasing and PLD Capital as nominee of the Company, and (iv) THE BANK OF NEW
YORK, a New York banking corporation ("BONY"), as Senior Note Trustee under the
Senior Note Indenture and Convertible Note Trustee under the Convertible Note
Indenture (as each term is defined below).

                                    RECITALS

         WHEREAS, the Company, NWE Cyprus, PLD Leasing, PLD Capital, WTC, BCL
and BONY, as trustee thereunder (the "Senior Note Trustee"), have entered into
the Indenture (as supplemented and amended, the "Senior Note Indenture"), dated
as of May 31, 1996, pursuant to which the Company issued $123,000,000 in
principal amount at Stated Maturity of its 14% Senior Discount Notes due 2004
(the "Senior Notes"; capitalized terms used herein without definition have the
respective meanings defined in the Senior Note Indenture as in effect on the
date hereof);

         WHEREAS, the Company, NWE Cyprus, PLD Leasing, PLD Capital, WTC, BCL
and BONY, as trustee thereunder (the "Convertible Note Trustee"), have entered
into the Indenture (as supplemented and amended, the "Convertible Note
Indenture"; together with the Senior Note Indenture, collectively the
"Indentures"), dated as of May 31, 1996, pursuant to which the Company issued
$26,500,000 in principal amount at Stated Maturity of its 9% Convertible
Subordinated Notes due 2006 (the "Convertible Notes");

         WHEREAS, the Company has formed PLD Capital Asset for the limited
purpose of operating as a Leasing Company;

         WHEREAS, Section 10.5 of each Indenture requires that the Company shall
cause each Subsidiary which, after the date of the Indentures, is required by
Section 4.10(a) of each
<PAGE>   2
Indenture to become a Guarantor to execute and deliver to the Trustee a
supplemental indenture in form and substance reasonably satisfactory to the
trustee which subjects such Restricted Subsidiary to the provisions of each of
the Indentures as a Guarantor;

         WHEREAS, PLD Capital Asset desires to enter into this Second
Supplemental Indenture and to become bound by the terms of each of the
Indentures as a Guarantor;

         WHEREAS, concurrently herewith, PLD Capital Asset and BONY, in its
capacities as Senior Note Trustee and Convertible Note Trustee and as collateral
agent thereunder (the "PLD Capital Asset Collateral Agent"), have entered into
the Leasing Company Security and Pledge Agreement (PLD Capital Asset) dated as
of the date hereof;

         WHEREAS, concurrently herewith, PLD Capital Asset and BONY, in its
capacities as Senior Note Trustee and Convertible Note Trustee and as escrow
agent thereunder (the "PLD Capital Asset Escrow Agent"), have entered into the
Leasing Company Escrow Account Agreement (PLD Capital Asset) dated as of the
date hereof;

         WHEREAS, all acts and things prescribed by the Indentures, by law and
by the Certificate of Incorporation and the Bylaws of the Company, of the
Guarantors and of BONY necessary to make this Second Supplemental Indenture a
valid instrument legally binding on the Company, the Guarantors and BONY in the
capacities in which it is a party hereto, in accordance with its terms, have
been duly done and performed;

         WHEREAS, all conditions precedent to amend or supplement the
Indentures have been met;

         NOW, THEREFORE, the parties hereto agree as follows:

         SECTION 1. Effect of this Second Supplemental Indenture. This Second
Supplemental Indenture is supplemental to the Indentures and does and shall be
deemed to form a part of, and shall be construed in connection with and as part
of, the respective Indentures for any and all purposes. Except as specifically
modified herein, the Indentures, the Senior Notes and the Convertible Notes are
in all respects ratified and confirmed and shall remain in full force and effect
in accordance with their terms.

         SECTION 2. Agreement to Become a guarantor Under the Indentures. PLD
Capital Asset shall become party to each of the Indentures as a Guarantor
thereunder and agrees to be bound by all the terms binding on a Guarantor
thereunder.

         SECTION 3. APPLICABLE LAW. THIS SECOND SUPPLEMENTAL INDENTURE SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

                                       -2-
<PAGE>   3
         SECTION 4. Counterparts. The parties may sign any number of
counterparts or copies of this Second Supplemental Indenture. Each signed
counterpart or copy shall be an original, but all of such executed counterparts
or copies together shall represent the same agreement.

         SECTION 5. Severability. In case one or more of the provisions in this
Second Supplemental Indenture shall be held invalid, illegal or unenforceable,
in any respect for any reason, the validity, illegality and enforceability of
any such provision in every other respect and of the remaining provisions shall
not in any way be affected or impaired thereby, it being intended that all of
the provisions hereof shall be enforceable to the full extent provided by law.

         SECTION 6. Headings. The headings, the language preceding the text of
the amendments and the sections in this Second Supplemental Indenture have been
inserted for convenience of reference only, are not considered a part hereof and
in no way modify or restrict any of the terms or provisions hereof.

                          [Signature pages to follow.]

                                       -3-
<PAGE>   4
         IN WITNESS WHEREOF, the parties hereby have caused this Second
Supplemental Indenture to be duly executed as of the date first written above.

                                        PLD TELEKOM INC. (formerly known as
                                        Petersburg Long Distance Inc.)


                                        By: /s/ Clayton A. Waite
                                           -------------------------------------
                                             Name: Clayton A. Waite
                                             Title: Vice President

                                        By: /s/ Clive Anderson
                                           -------------------------------------
                                            Name: Clive Anderson
                                            Title: Senior Vice President


                                        NWE CAPITAL (CYPRUS) LIMITED



                                        By: /s/ Clayton A. Waite
                                           -------------------------------------
                                             Name: Clayton A. Waite
                                             Title: Authorized Representative



                                        PLD ASSET LEASING LIMITED

                                        By: /s/ Clayton A. Waite
                                           -------------------------------------
                                             Name: Clayton A. Waite
                                             Title: Director


                                        PLD CAPITAL LIMITED


                                        By: /s/ Clayton A. Waite
                                           -------------------------------------
                                             Name: Clayton A. Waite
                                             Title: Director

                                      -4-
<PAGE>   5
                                        PLD CAPITAL ASSET (U.S.) INC.


                                        By: /s/ E. Clive Anderson
                                           ----------------------------------
                                             Name: E. Clive Anderson
                                             Title: Vice President


                                        WIRELESS TECHNOLOGY CORPORATIONS LIMITED


                                        By: /s/ E. Clive Anderson
                                           ----------------------------------
                                             Name: E. Clive Anderson
                                             Title: Authorized Representative


                                        BALTIC COMMUNICATIONS LIMITED


                                        By: /s/ E. Clive Anderson
                                           ----------------------------------
                                             Name: E. Clive Anderson
                                             Title: Authorized Representative

                                        /s/ Clayton A. Waite
                                        -------------------------------------
                                        CLAYTON WAITE

                                        APROPOS INVESTMENTS LTD.


                                        By: /s/ Clayton A. Waite
                                           ----------------------------------
                                             Name: Clayton A. Waite
                                             Title: Authorized Representative

                                      -5-
<PAGE>   6
                                        THE BANK OF NEW YORK, as Senior Note
                                        Trustee and Convertible Note Trustee.


                                        By: /s/ Thomas E. Tabor
                                           ---------------------------------
                                             Name: Thomas E. Tabor
                                             Title: Assistant Vice President



                                      -6-