Turkey's President, Recep Tayyip Erdogan, left, and Russian President Vladimir Putin, shake hands following the group photo at the World Energy Congress, in Istanbul, Turkey, Oct. 10. The two countries are discussing a cease-fire plan for Syria. With his victory in Aleppo, Syrian President Bashar Assad appears to have survived a nearly six-year war to drive him from power.

BEIRUT — Turkish and Russian officials are discussing the contours of a cease-fire for Syria, Syrian opposition factions said, building on cooperation between the two countries following a deal they brokered for the evacuation of opposition fighters from the northern city of Aleppo earlier this month.

Several rebel groups said that they are withholding approval of any agreement until they receive details about its terms.

An official with one of the factions said that Russian and Turkish officials were debating a cease-fire proposal that would encompass the whole of Syria. He spoke on condition of anonymity because the talks were ongoing. Rebels have spoken up in the past against proposals that would allow the government to continue its offensives around the outskirts of the capital, Damascus.

Turkey’s Anadolu Agency said this morning that Ankara and Moscow had reached an agreement, but there was no confirmation from state officials.

The Syrian opposition official said factions were holding vigorous discussions over the possibilities.

Another official with a different group said the proposal has not been formally presented to the opposition.

“It is difficult to accept or refuse the matter before we look at the details, of course,” said the official, who also spoke on the condition of anonymity so as not to bias talks.

The report said a plan would be presented to all sides of the conflict and aims for a cease-fire that would come into force “in all regions” where fighting between pro-government forces and opposition groups is taking place. It quoted unnamed officials.

Terror organizations would be kept out of the scope of the cease-fire agreement, the agency said, without elaborating on which insurgent groups would be considered terror organizations.

It said a peace process in Kazakhstan’s capital of Astana would go ahead under Russia and Turkey’s leadership if the cease-fire holds. Anadolu said the two countries would act as “guarantors” of the peace process.

Russian President Vladimir Putin’s spokesman confirmed Russia and Turkey were in “constant contact” to prepare for planned Syria peace talks in Kazakhstan, but did not comment about the possibility of a cease-fire.

In the U.N., a top Russian diplomat said a draft U.N. Security Council Resolution that would impose sanctions on Syria for chemical weapons use is unacceptable to Moscow, which has veto power on the council.

The resolution would impose sanctions on an array of Syrian individuals, organizations and companies allegedly involved in chemical weapons attacks. It would also ban sales of helicopters to Syria.

Deputy Foreign Minister Sergei Ryabkov was quoted by the state news agency Tass today as saying the resolution “is categorically unacceptable to us. We warn them against attempts to fan tensions in the U.N. Security Council.”