Syrian troops and its allied forces advanced overnight seizing Aleppo's Tariq al-Bab neighbourhood from rebels as they press an offensive to recapture all of the city, a monitor group has said.

The capture of the neighbourhood means the government has now retaken around 60% of the east of the city, which the rebels overran in mid-2012, the Syrian Observatory for Human Rights said.

The advance also restores control of a road leading from government-controlled western neighbourhoods of the city to Aleppo airport, which the regime also holds.

The government's capture of Tariq al-Bab came after ferocious clashes that sent civilians flooding out of the adjacent neighbourhood of Al-Shaar.

An AFP correspondent saw only a few rebel fighters in the district yesterday as the government advanced, with shops and bakeries shuttered and vegetable stalls shattered by heavy shelling. 

More than 300 civilians have been killed in east Aleppo since the government resumed its offensive to oust the rebels on 15 November.

The United Nations has warned that the sector risks becoming a "giant graveyard" for the 250,000-plus civilians who were trapped there just last week.

Tens of thousands have since fled.