The Security Council has agreed to end the UN military observer mission in Syria in the face of an escalating civil war.
The council backed a new liaison office in Damascus to support UN and Arab League efforts to end the country's 18-month conflict.
France's UN ambassador Gerard Araud, the current Security Council president, said members who have been deeply divided on tackling the conflict were united behind UN secretary-general Ban Ki-moon's proposal to replace the 300 unarmed observers with a small group of military advisers and political, human rights and civil affairs experts.
Mr Araud said the council agreed that conditions set for possibly extending the observer mission - a significant reduction in violence and an end to the Syrian government's use of heavy weapons - had not been met and the mission's mandate would end on Sunday.
The mission has been severely limited in its work by the violence in Syria, and members have been mainly confined to their hotels since June 15.
Russia's UN ambassador Vitaly Churkin, whose country is the most important ally of Syrian president Bashar Assad, invited UN ambassadors from key nations and regional and international organisations who agreed in June in Geneva on guidelines for a Syrian-led political transition to a meeting on Friday at UN headquarters in New York.
Mr Churkin told reporters he wants the Geneva action group - along with "important actors" Iran and Saudi Arabia, who are not members - to make "a joint or parallel appeal to all the parties of the Syrian conflict that they end violence as soon as possible by a certain point in time".
He said the appeal should also urge the government and opposition to appoint representatives "to negotiate towards a political solution, and in particular towards the establishment of a transitional governing body as provided for in the Geneva document".
In a letter to the council last Friday, Mr Ban said the conditions for extending the observer mission had not been met, but he added that "it is imperative for the United Nations to have a presence in Syria" aside from its humanitarian operation in order to support UN and Arab League efforts "in mediating and facilitating a peaceful resolution to the crisis".
UN assistant secretary-general for peacekeeping Edmond Mulet told reporters that the observer mission "will come to an end at midnight on Sunday". There are currently 101 observers and 72 civilian staff members in Syria, he said. In order to have an orderly departure, the last observers will leave on August 24, but they will not do any work after Sunday. Mr Mulet said discussions are under way on the new UN liaison office, which he said has been approved by the Syrian government and will have about 20-30 staff members.