Syrian security forces Friday opened fire on demonstrators in the town of Kiswah, south of Damascus, injuring an unknown number of people, an activist told AFP by telephone.

"The security forces opened fire to disperse demonstrators in Kiswah and there are reports of injuries" among the protesters, said Rami Abdel Rahman, of the London-based Syrian Observatory for Human Rights.

Other rights activists said that thousands of people took to the streets in several Syrian cities and towns after the weekly Muslim prayers calling for the fall of the autocratic regime of President Bashar al-Assad.

Protests were also reported in Damascus and demonstrators braved security forces despite the arrests of some of them, the activists said.

The Facebook group Syrian Revolution 2011, one of the motors of the protests, has called on Syrians to stage more rallies after the main Friday Muslim prayers.

The theme for the protests, it said, is "Bashar is no longer my president and his government no longer represents me."