Two children were among the dead in the attack which occurred late Thursday in the Massaken Barzeh district, the Britain-based watchdog said.

The official SANA news agency said the bomb struck a petrol station near a hospital and that it also wounded many civilians.

The Syrian Revolution General Commission (SRGC) activist network also reported the attack, adding that large numbers of troops deployed in the neighbourhood afterwards.

Nationwide at least 160 people died in violence on Thursday, including 72 civilians, said the Observatory, which gathers information from a network of medics and activists.

On Wednesday, the United Nations said the overall death toll from the 21-month conflict had topped 60,000.