AMMAN: Syrian fighter plane attacks on eastern suburbs of Damascus killed at least 60 people on Monday, opposition activists said.

They said the aerial attacks targeted the neighbourhood of Zemalka and the more easterly suburb of Saqba where Free Syrian Army fighters had attacked and overrUn several army roadblocks earlier in the day.

Both suburbs are predominantly Sunni Muslim. Sunnis have been at the forefront of 17 months of fighting against President Bashar al-Assad.

Moreover, the United States says more than 300 people were killed in fighting in the suburbs of the Syrian capital over the weekend.

Syrian opposition activists say as many as 600 people were killed by government forces in the Damascus suburb of Daraya.

US State Department spokeswoman Victoria Nuland said Monday some 150 of the victims had been killed in a single location. She cited reports from human rights activists that some were killed point-blank ''in the most brutal way at the hands of the regime.''

Despite the escalating violence, Nuland did not endorse a call from French President Francois Hollande for the fractured Syrian opposition to form a provisional government to rival President Bashar Assad.

She said it was a decision for Syrians to make for themselves.