Regime warplanes bombed the town of Moadamiyet al-Sham, southwest of the capital, the Syrian Observatory for Human Rights said.

Warplanes also attacked the towns of Shebaa to the southeast and Deir Assafir south of Damascus, where 11 children were killed in November when cluster bombs were dropped on a playground, according to Human Rights Watch.

The deadly strikes came as forces loyal to President Bashar al-Assad battled rebels with artillery fire in Harasta and Douma, insurgent strongholds to the northeast of the capital, and in Daraya to the southwest.

Army reinforcements have been massing for weeks in Daraya in a bid to drive rebel Free Syrian Army fighters from the town, the site of the bloodiest massacre of the conflict in which hundreds died in August.

Northeast of Damascus, the army shelled Qaboon district, the Observatory said, while in the south, residents of a Palestinian refugee camp that faced deadly air raids in December fled once again amid mortar attacks.

The Syrian conflict, which started as a peaceful uprising against Assad in March 2011 but descended into civil war when it was violently suppressed, has killed more than 46,000 people, many of them civilians, according to the Britain-based Observatory.

The Observatory relies on a network of activists and medics on the ground for its information.