Assad's forces are closing in on eastern Aleppo after warning rebels and civilians to leave the opposition-held districts.
Syrian regime soldiers using megaphones called on the remaining fighters and civilians to exit as they prepare to take full control of the city, a military source said.
"The army is expected to enter Aleppo to clean the area after the fighters leave," the source said.
TRT World's Abubakr al Shamahi reports from Gaziantep on developments.
Regime allies Russia and Iran held talks with Turkey in Moscow on Tuesday to start brokering a new peace deal in Syria.
The foreign ministers of the three countries had agreed to expand the ceasefire, Russian Foreign Minister Sergey Lavrov said, adding he expected the evacuation of the city to be completed in a day or two.
Turkish Foreign Minister Mevlut Cavusoglu said 37,500 people had been ferried out of the last rebel-held enclave in eastern Aleppo.
The regime and other parties on the ground have also agreed to allow 20 United Nations observers to be sent to the city to monitor evacuations.
UN spokesperson Ingy Sedky said 750 people had been evacuated from the rebel-controlled Shia villages of Fuaa and Kafraya, in northwest Syria, as part of the deal.
Nearly 500 people have been killed, including women and children, since mid-November when regime forces backed by their allies intensified their operation to retake control of eastern Aleppo.
The evacuation of Aleppo's rebel sector is seen as a pivotal moment in the nearly six-year war that has killed 500,000 people and triggered a humanitarian and refugee crisis.