Russia says it will hold talks with the United States on a complete rebel withdrawal from the Syrian city of Aleppo, where forces allied to the Syrian government have made sweeping advances.
Syrian rebel groups, however, rejected the idea of evacuating Aleppo, around two-thirds of which has been seized by government forces in recent weeks.
Russian Foreign Minister Sergei Lavrov said talks with Washington on the withdrawal of rebels would begin in Geneva on December 6 or 7.
There was no immediate comment from Washington, which has backed some of the rebels.
"Those armed groups who refuse to leave eastern Aleppo will be considered to be terrorists," Lavrov told reporters on December 5. "We will treat them as such, as terrorists, as extremists and will support a Syrian army operation against those criminal squads."
But rebel groups swiftly rejected any talk of an evacuation.
Yasser al-Youssef of the Nureddine al-Zinki faction, a leading rebel group in Aleppo, told the AFP news agency that any such proposal was "unacceptable."
"No person in his right mind, who has any sense of responsibility and patriotism, would leave his city," rebel official Zakaria Malahifji told Reuters.
Based on reporting by Reuters and AFP