Syrian opposition forces lost all of the northern neighbourhoods of their stronghold in east Aleppo on Monday (November 28th), as the regime made significant advances in its offensive to recapture the entire city, AFP reported.

The fighting has prompted an exodus of thousands of civilians.

"The situation is disastrous," said Ibrahim Abu al-Leith, a spokesman for the White Helmets rescue group in Ansari neighbourhood."There is mass displacement and morale is in the gutter."

On Monday, regime forces seized the Sakhur, Haydariya and Sheikh Khodr districts, and Kurdish fighters took the Sheikh Fares neighbourhood from opposition forces, the Syrian Observatory for Human Rights said.

Observatory director Rami Abdel Rahman described this as the opposition's "worst defeat since they seized half the city in 2012".

The advances left all of north-east Aleppo under regime control, and mean the regime now controls at least a third of eastern Aleppo.

On Sunday night, the Observatory said nearly 10,000 civilians had fled the east, with around 6,000 moving to the Kurdish-held Sheikh Maqsud neighbourhood and 4,000 to regime-held west Aleppo. Civilians also were fleeing south to the remaining opposition-held districts.

The assault has been waged with heavy airstrikes, barrel bomb attacks and artillery fire that has killed at least 225 civilians, including 27 children, in east Aleppo, according to the Observatory.

Opposition fire into the regime-held west also has killed at least 27 civilians, among them 11 children, since November 15th, the Observatory said.