The UN said Thursday that it had deployed dozens of observers in east Aleppo to monitor the last stage of an evacuation, which is clearing the way for Syria's army to retake the city.
"Thirty-one staff are now assigned for monitoring," Jens Laerke, spokesman for the UN humanitarian agency, told AFP, adding that the observers included both national and international staff members.
"They are all on the job right now," he said.
The announcement came as the evacuation of rebel fighters and civilians from the onetime opposition stronghold appeared to be reaching its final hours.
"A very large, dangerous, difficult and complex evacuation is going into its final phase today," the head of the UN-backed humanitarian taskforce for Syria, Jan Egeland, told reporters in Geneva.
He said that as of Thursday morning, some 35,000 people had left Aleppo.
"It's very complex," he said, stressing the importance of having UN monitors on site.
"Presence means protection," he said.
The green light for the monitoring mission came after the UN Security Council unanimously adopted a resolution on deploying the monitors to oversee the evacuation and report on the protection of civilians who remain in the besieged city.
The Syrian government agreed earlier this week to allow the UN to send 20 observers from Damascus to monitor the east Aleppo evacuations, and they had begun arriving late Tuesday, Laerke said.
The remaining monitors had been drawn from a contingent of around 100 UN staff members already on the ground in Aleppo and had been reassigned from other tasks, he said.
- Desperate situations -
Laerke said all the monitors had been deployed at the crossing-point into Ramussa, the government-held district of southern Aleppo through which evacuation convoys have been leaving.
"This is a 24-hour operation, so we are taking them in and out in shifts," he explained, adding that there was a "rotation so that we man (the crossing-point) constantly, because the movement has been constant."
The monitors had seen desperate situations as people continued to pour out of the last rebel-held enclave, braving a snowstorm and freezing temperatures, Laerke said.
"It's been a very difficult night. The weather is really harsh, and people are leaving in hundreds of private vehicles at different levels of disrepair," he said, saying the evacuation had been stop and go, as cars broke down and people were forced to get out and push.
Egeland meanwhile said that more than 200 buses had been used for the evacuation, as had more than 750 cars and trucks, many with flat tyres or no fuel, but crammed full of people.
The evacuation of Aleppo's rebel sector is a pivotal moment in a war that has killed more than 310,000 people and triggered a major humanitarian and refugee crisis.
The retreat from Aleppo -- which had been divided into a rebel-held east and government-controlled west since 2012 -- marks the biggest victory for President Bashar al-Assad's forces in nearly six years of civil war.
