About 25,000 people have been evacuated from the rebel-held enclave of Aleppo since Thursday, the International Committee of the Red Cross has said.

About 15,000 people were brought to safety yesterday and 10,000 others last Thursday.

Teams from the ICRC and the Syrian Arab Red Crescent, who are leading the evacuation, were "working through the night", ICRC spokeswoman Krista Armstrong said.

Thousands of people are said to be still waiting to be bussed out.

Syria's army has urged the last remaining rebels and civilians to leave the bombed-out eastern quarters of Aleppo, a military source said.

"The army is expected to enter [Aleppo] to clean the area after the fighters leave," the source said.

He said soldiers "issued a call over megaphones to the remaining fighters and civilians who want to leave, to exit the eastern districts".

Thousands of people started being evacuated from Syria's second city since a landmark deal - brokered by Turkey and Russia - was reached last week.

The agreement for civilians and rebels to quit the last sliver of opposition-controlled territory in the city paves the way for the government to declare full control over Aleppo.

Aleppo was once Syria's commercial and industrial hub, but it has been divided since 2012 between government forces in the west and rebel control in the east.

Government forces launched an offensive in mid-November to capture the whole city, and had seized more than 90% of the eastern half when the evacuation deal was struck.

More than 310,000 people have been killed since Syria's conflict erupted in March 2011, and millions more have been displaced.