''I have th<:: honour to infonu you that your letter dated 21 June 1991 144 concerning the appointment of the Force Commander of the Military Unit of the United N~o~tions Mission for the Rderwdum in Western Sahara h~; been brought tu the aw:ntion of the members of the Security Council and that y<)ur proposal meets with their appr<)Val." In a letter dated 8 July 1991 146 addressed to the President c,f tht; Security Council, the Se,:retary-General referred to his report of 18 June 1990 to the Security Council on the situation '~oncerning Western Sahara142 and stated that in accordance with paragraph 12 or that report. he had addressed identical letters on 24 May 1991 to Morocco and the Frente Popular para .la liberad6n de Saguia ei-Hamra y de Rio de Oro proposing a specific date and hour for the formal cease-fire to hegin. In letters dated 11 June 1991 and 10 hme 1991, respectively, Morocco and tbe Frente Popular had infonned the Secretary-General of their acceptance of his proposal that the formal cease-fire should begin at Ofim GMT on 6 September l';i91. In a letter dated 3 September 1991w addressed to the President of the Security Council, the Secretary··General, in <.11::cordance with the United Nations plan for the referendum in We,stem Sahara as described in his report of 18 June 1990142 ;md amplified in his report of 19 April 1991,143 and with re1;olution 690 (1991) of 29 April 1991, transmitted to the President of the Security Council a note regarding the implementation of the cease-fire. TI1e Secretary-General stated that, concerned at recent developments along the international frontier, he had decided that United Nations efforts should be concentrated, at this stage. in the areas referred to in the note, that is Aguenit, Awsard, Bir Lahlot;, Mahbes, Meharrize, Mijek, Oum Dreyga, Smara, Tifariti. and Zug. In this context, he recalled that paragraph 20 of his report of 18 June 1990 stipulated that the establishment and functioning of the obseJVer group would be in accordance with the general princ1ples applicable to United Nations peace ..keeping operations. Jn a letter dated 4 September 1991,148 the President of the Security Council informed the Secretary-CJeneral as follows: "1 have the honour to intorm you that I have brought to the attention of the members of the Security Council your letter dated 3 September 1991147 concerning the situation in Western Sahara. "'The members ofthe Council endorse your action and continue to ~;upport your efforts." ln a letter dated 13 September 1991 149 addressed to the President of the Security Council, the Secretary-G-eneral referred to the United Nations plan for the referendum in Wc~tem Sahara as described in his report of 18 June 1990142