Some 50,000 civilians have fled eastern Aleppo over the past two days in a "constant stream", Russia says, as Syrian government forces close in on the last pocket of opposition control.
Russian Defence Ministry spokesman Major General Igor Konashenkov said Syrian troops have suspended their offensive to allow the evacuation of civilians.
However, the activist-run Syrian Observatory for Human Rights says heavy clashes are still under way.
Mr Konashenkov said that on Saturday alone more than 20,000 civilians left rebel-controlled Aleppo districts through humanitarian corridors. The military is live streaming images from drones showing the exit.
Backed by Russia and other allies, Syrian president Bashar Assad's forces have driven the rebels from nearly all of eastern Aleppo, which was captured by the opposition in 2012.
The UN human rights office has expressed concern about reports that hundreds of men have vanished after crossing from eastern Aleppo into government-controlled areas.
US secretary of state John Kerry and European and Arab diplomats are meeting members of Syria's opposition in Paris.
Mr Kerry said he is working to ensure their safety and to save Aleppo "from being absolutely, completely destroyed".
US and Russian military experts and diplomats are meeting in Geneva to work out details of the rebels' exit from eastern Aleppo.
It comes after US defence secretary Ash Carter said as many as 200 more US troops are being sent to Syria to help Kurdish and Arab fighters capture Islamic State's key stronghold of Raqqa,
The extra troops will include special operations forces and are in addition to 300 already authorised for the effort to recruit, organise, train and advise local Syrian forces to combat IS.
Addressing a security conference in Bahrain, Mr Carter said the extra troops will help local forces in their anticipated push to retake Raqqa, the de facto capital of the extremist group's self-styled caliphate, and to deny sanctuary to IS after Raqqa is captured.