Some rebels in Eastern Ghouta may soon agree to withdraw from the opposition enclave or accept rule by the Syrian state after big advances by the army into the area, a Syrian government minister has said.

Syrian government forces have splintered Eastern Ghouta into three separate zones in a month-long assault to crush the last major opposition stronghold near Damascus, confronting the rebels with their biggest defeat since 2016.

Damascus and its Russian allies are offering rebels in Eastern Ghouta similar terms to those offered in other parts of the country that have been recaptured: safe passage out for those who agree to surrender territory, or a reconciliation agreement for those who wish to stay under government rule.

Ali Haidar, the Syrian minister responsible for such agreements, has said that rebels in an enclave centred around the town of Harasta - one of three rebel pockets in Eastern Ghouta - may be ready for such a deal.

Mr Haidar said there were contacts with Ghouta rebels and "to a certain extent there are acceptable results in part of the file".

He added: "There may be an accomplishment in Harasta in the coming period.

"I don't commit to specific timeframes because the matter is linked to the militants accepting departure or settling their situation (with the authorities) and the army entering the area," he said.

He said: "what remains of Ghouta is, I believe, open to discussion ... to accomplish reconciliations at a certain level".

It comes as at least 20 civilians have died in a resumption of bombing on Douma, the largest town in the rebel-controlled pockets of Eastern Ghouta, according to the Syrian Observatory for Human Rights.

Thirteen were killed late on Sunday in air strikes and artillery fire on the battered town, and another seven were killed this morning, according to the monitor.

The fresh bloodshed came after a week-long lull in the bombardment of Douma after negotiations between rebels and regime-backer Russia allowed medical evacuations from the town.

Syria's government has pressed a ferocious month-long air and ground on Ghouta in a bid to clear the last rebel bastion on the capital's outskirts.

More than 1,400 civilians including 281 children have been killed, according to the Britain-based Observatory.

Troops have captured more than 80% of the enclave and split the remaining rebel territory into three pockets, with Douma in the northernmost zone.