More than 10,000 civilians have fled eastern parts of Aleppo in the past 24 hours for districts of the city under the control of Syria's government, a monitor said Monday.

It takes to about 130,000 the number of civilians displaced since regime forces launched an offensive to retake the rebel-held east in mid-November, said the Syrian Observatory for Human Rights.

Pro-government forces on Monday seized the Aleppo district of Sheikh Saeed, putting it in control of 90 percent of areas once held by the rebels, the Britain-based monitoring group said earlier.

Observatory director Rami Abdel Rahman said the advance has left some neighbourhoods of the battleground northern city empty of civilians.

Syria's second city, Aleppo had been divided since 2012 between government forces in the west and rebel groups in the east.

In less than a month, a blistering offensive by Syria's army and allied militia has overrun most of rebel territory in the city.