Syria's army on Saturday pressed a fierce assault launched four days ago against rebel areas in northern and eastern Damascus, killing three children with mortar fire, a monitoring group said.
"The district of Qaboon in (northeastern) Damascus is being intensely shelled by regime forces," the Syrian Observatory for Human Rights reported.
Rebels were resisting the onslaught, battling troops loyal to President Bashar al-Assad on the edges of Qaboon as the army tried to storm the neighbourhood, it said.
Overnight mortar fire targeting Qaboon killed three children from one family, the Britain-based group said.
Nearby, clashes raged between rebels, troops and pro-Assad militiamen in the Barzeh neighbourhood of the capital, said the watchdog.
The fighting erupted as rebels fought off an army attempt to enter the district, said the Syrian Revolution General Commission, a network of activists on the ground.
Battles also raged on the edges of Al-Hajar al-Aswad in southern Damascus and Jubar in the east, said the Observatory. Troops meanwhile pounded the Qadam district, parts of which are rebel-held.
Over the past fortnight, the army has dramatically boosted efforts to crush the anti-Assad insurgency in and around Damascus.
The opposition and activists have warned of critical humanitarian conditions in some areas.
Also on Saturday, the military pushed on with its bid to end the insurgency in and around Homs in central Syria, said the Observatory.
While troops shelled rebel-held besieged districts in the heart of Homs city, Assad loyalists also tried to storm the town of Tal Kalakh near the border with Lebanon.
Referred to by activists as "the capital of the revolution", Homs has suffered massive damage during Syria's 27-month conflict.