BEIRUT – Syrian troops shelled rebellious areas in central and northern Syria on Saturday in the latest push to quash the uprising against President Bashar Assad, but faced fierce resistance from army defectors, activists said.

Much of the day’s fighting focused on the northeastern town of Saraqeb, which activists said regime troops and tanks entered from the north amid heavy shelling.

The Britain-based Syrian Observatory for Human Rights said fighting reached the central market district, where army defectors damaged a tank and three armored personnel carriers. Late Saturday, it said two rebel fighters and nine government troops had been killed in the clashes.

“Large numbers of residents are fleeing the town,” said Rami Abdul-Rahman, who heads the Observatory, which has a network of activists inside Syria. “People have been leaving the town for some time but after today’s attack the process intensified.”

Government troops also shelled parts of the central city of Homs and the nearby town of al-Qusair. Activist videos posted online Saturday showed explosions in residential neighborhoods sending up balls of flame and huge plumes of smoke.

The Observatory said 14 people were killed Saturday in Homs province. Another group, the Local Coordination Committees, put the death toll there at 24. Both said more than 40 people were killed nationwide.

Syria’s government has been on the offensive over the past two months and has pushed rebels from a number of strongholds: the provincial capital and other towns in the northwestern province of Idlib that borders Turkey, the central provinces of Hama and Homs, and the eastern oil-rich region of Deir el-Zour that borders Iraq.

Syria’s rebels, who took up arms following the regime’s crackdown on protesters, are outgunned by armored units loyal to Assad, but have adopted a tactic of hit-and-run strikes on security checkpoints and convoys. They killed at least six soldiers in such attacks Saturday, the Observatory said.

The Syrian government cites the rise in such attacks to boost its argument that the uprising is being carried out by terrorist groups acting out a foreign conspiracy.

The Syrian state news agency said an “armed terrorist group” blew up a natural gas pipeline in the country’s east Saturday, causing the leakage of 700,000 cubic meters of gas. The agency said the pipeline feeds a fertilizer factory and electric plant in Homs, and that the damage would take three days to repair.

The LCC said the troops that entered Saraqeb were accompanied by pro-government gunmen and plainclothes security agents who arrived in buses and started conducting raids and detaining people.