Syrian President Bashar al-Assad's forces killed at least 12 people on Saturday and injured 30 in a bombardment of suburbs of Damascus that have fallen under rebel control, activists said.

About half of those killed were civilians. The rest were army defectors loosely grouped under the Free Syrian Army, they said.

Most were casualties of anti-aircraft gunfire and mortar rounds that hit the suburbs of Saqba, Hammouria and Kfar Batna on the eastern edge of the Syrian capital, known as al-Ghouta, they added.

The injured are at field hospitals, but there has not been any electricity in al-Ghouta for days. Only a few people have fled because the army has cut off the area from Damascus and blocked it off from the main highway north, Kamal, one of the activists, told Reuters by phone from the area.

(Reporting by Khaled Yacoub Oweis, Amman newsroom; editing by David Stamp)