Reports from Syria say government troops are mounting new attacks on areas in the suburbs of Damascus where opposition forces have established centres of resistance.
The BBC reports tanks are said to be shelling rebel areas in the east and north of the city.
The latest army offensive started on Saturday in the eastern suburbs of Kfar Batna, Saqba, Jisreen and Arbeen.
More than 2000 troops and 50 tanks reportedly joined the operation on Sunday, 5km from the city centre.
However, such reports are difficult to verify because of government restrictions on the media.
On Saturday the Arab League announced it was halting its observer mission for the time being, because of the ongoing fighting.