Russian representatives have held talks in Ankara with Syrian rebels opposed to President Bashar al-Assad over the possibility of a truce in the divided city of Aleppo, a source said today.
Russia is Assad's main international ally and has intervened militarily to help his forces regain full control of Aleppo in northern Syria.
But concern is growing over the humanitarian situation in Syria's battered second city as Assad's forces press an offensive, depriving inhabitants of the rebel-held east of aid.
"Several meetings have taken place in Ankara to discuss the ways to come to such a truce," said a source close to Syria's rebel factions who asked not to be named.
The last meeting in the Turkish capital took place on Monday, the source said, without saying who had taken part.
Those involved are linked to the opposition Syrian National Coalition and do not include jihadists from the Fateh al-Sham Front, the new name for Al-Nusra Front after it severed ties with Al-Qaeda.
The discussions come as Assad's forces backed by Russia make major progress in their bid to control the city. Should they succeed, it would be the rebels' biggest setback of the war.
The UN's Syria envoy Steffan de Mistura on October 6 urged Fateh al-Sham to leave eastern Aleppo, and Russia and the Syrian regime to stop their bombing once the jihadists depart.
Turkey is also pressing an unprecedented military incursion inside Syria, backing pro-Ankara rebels as they fight Islamic State (IS) jihadists and a Kurdish militia.
Ankara has repeatedly pushed for the ouster of Assad as the only solution to end the Syrian civil war.
But Turkey has been noticeably muted in its criticism of Russian actions in Aleppo since a deal to normalise ties with Moscow in June following a sharp diplomatic crisis over the shooting down of a Russian plane.
Turkish Foreign Minister Mevlut Cavusoglu met today with Riad Hijab, head of the opposition High Negotiations Committee, with the two discussing "efforts to stop the fighting immediately and to deliver humanitarian aid as soon as possible" to Aleppo, diplomatic sources said.