Damascus: At least 30 people were killed in 24 hours in the central Syrian city of Homs in clashes between supporters and opponents of President Bashar al-Assad's regime, a human rights activist said.

The deaths came as the army moved in on two border towns in the east and west seeking to quell anti-regime protest.

"More than 30 civilians have been killed over the past 24 hours in Homs in clashes that broke out late on Saturday between the opposition and supporters of the regime," Rami Abdel Rahman of the London-based Syrian Observatory for Human Rights said on Sunday.

He said the clashes in the city 160 km north of the capital came after three regime supporters kidnapped last week were killed and their dismembered bodies were returned to their relatives on Saturday.

"These clashes are a dangerous development that undermines the revolution and serves the interests of its enemies who want it to turn into a civil war," he added.

"The two sides started out beating each other with sticks, but then firearms were used."

Abdel Rahman said a large number of the dead were killed by gunmen lying in ambush, and that security forces did not intervene.

"Their duty is to maintain national security and protect citizens, not stand idly by when faced with clashes, as this can encourage even more violence," he charged.

A witness who spoke to a news agency in Cyprus said the clashes were between Sunni Muslims and Alawites, Assad's sect, and that they occurred overnight in the Hadara and Al-Zahara districts of Homs.