"It is the intention of the United Nations to convene those negotiations in Geneva on 8 February 2017," UN envoy Staffan de Mistura said after the Security Council unanimously adopted a French-drafted resolution to monitor evacuations from Aleppo, with Russia's backing.
But in Moscow, President Vladimir Putin said after Russian ambassador to Turkey Andrei Karlov was shot dead by a policeman in Ankara that the killing could "disrupt" the peace process in Syria and harm Turkish-Russian ties.
James Nixey, head of the Russia and Eurasia programme at think tank Chatham House, said the diplomat's murder could affect Aleppo evacuations.
Families in Aleppo had spent hours waiting in below-freezing temperatures, sheltering from the rain in bombed-out apartment blocks and waiting desperately for news of a new wave of departures.
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After an agonising delay, the operation resumed under a complex agreement that will see regime forces exert full control over Syria's second city.
Buses transported more than 7,000 people out of the city, said Ingy Sedky, spokeswoman for the International Committee of the Red Cross (ICRC).
"There are still thousands -- it's a huge crowd, women, children," she said.
The evacuees included seven-year-old Bana al-Abed, whose Twitter account had offered a tragic account of Syria's nearly six-year war, as well as 47 children who had been trapped in an orphanage.
Ahmad al-Dbis, who heads a team of doctors and volunteers coordinating evacuations, saw dozens of buses and ambulances arrive at the staging ground west of Aleppo.
He said the evacuees were in "a very bad state after waiting for more than 16 hours" at a regime checkpoint without being allowed off the vehicles.
The ICRC and the Syrian Observatory for Human Rights said around 500 people left in a dawn convoy out of Fuaa and Kafraya.
The Britain-based Observatory said at least 14,000 people, including 4,000 rebels, have left the opposition sector since the evacuations began on Thursday while at least 7,000 remain.