AMMAN: A car bomb exploded on Tuesday in a Sunni Muslim district of the Syrian capital Damascus, killing and wounding dozens of people, opposition activists said.

They said the attack occurred hours after a bombing in a neighbourhood populated by members of President Bashar al-Assad's minority Alawite sect. That bombing killed at least 10 people, according to state media.

The second bomb, placed in a parked taxi, went off near a mosque in the southern working class neighbourhood of al-Qadam. Buildings were damaged and bodies were buried under debris that filled streets in the area, the activists told Reuters by telephone.

"Lots of people were hit inside their apartments. Rescue efforts are hampered because electricity was cut off right after the explosion," said Abu Hamza al-Shami.

"There is a state hospital nearby but we are afraid to take the wounded there because they could be liquidated."

Other activists in other area of Damascus said the sound of the explosion shook windows many kilometres (miles) away. One reported seeing a big bright flash before hearing the bomb go off.

Bomb attacks along sectarian lines have escalated lately in the 19-month-old uprising against Assad. Last month several bombs exploded during the Muslim Eid holiday near mosques in Sunni districts and the Damascus suburbs, killing and injuring dozens of people, activists said.