The Syrian Observatory for Human Rights, based in London, and the Local Coordination Committees said the troops entered Saraqeb from the north and were advancing while tanks fired on the town.
The Observatory said that fighting had reached the central market district and that several members of the military and a civilian were killed, with dozens more wounded.
“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.”
The violence in Syria has shown no signs of abating despite renewed diplomatic efforts to halt the fighting that has killed more than 8,000 people, according to United Nations estimates. The Security Council last week unanimously endorsed an effort by Kofi Annan, the former United Nations secretary general, to broker a cease-fire, and he was expected to meet Russia’s president, Dmitri A. Medvedev, on Sunday to move that initiative along.
Russia and China, another scheduled stop on his trip, have been some of the most steadfast supporters of President Bashar al-Assad of Syria. Although their backing appears to have weakened recently, it is unclear how far either country will go in pressuring Mr. Assad to end the government’s brutal crackdown.
Mr. Assad has insisted from early in the uprising that his government is under assault by terrorists despite the mostly peaceful nature of the original protests. Since then, the conflict has become more violent as defectors and others have taken up arms against Mr. Assad’s forces.
Syria’s government has been on a renewed offensive over the past two months, pummeling the city of Homs and now advancing on areas farther north.
Syria’s rebels are outgunned by armored units loyal to Mr. Assad but have opted for hit-and-run raids and ambushes.
The Local Coordination Committees said the troops entering Saraqeb, in Idlib Province, this weekend were accompanied by pro-government gunmen known as shabiha and plainclothes security agents who arrived in buses and started conducting raids and detaining people. Calls to the town could not get through. The government is known to cut networks in areas where military operations are under way.
The attack came less than two weeks after troops struck hard at the city of Idlib, the provincial capital, which rebels controlled for months.
The Observatory said Syrian security forces killed 10 people in Syria on Saturday while the Local Coordination Committees put the death toll at 15.
Earlier on Saturday, the Observatory and the committees said troops fired mortar rounds at the rebel-held neighborhood of Khaldiyeh in Homs, raising fears that troops would enter the area soon.
A recent offensive lasting weeks against Homs targeted the neighborhood of Baba Amr, which was heavily damaged. Government forces forced their way back into the neighborhood, but many of the rebels moved to other parts of the city. The Observatory said Khaldiyeh, which is heavily populated, had been shelled since early Saturday. The Local Coordination Committees posted a video on its Facebook page showing smoke billowing from a residential area it said was in Khaldiyeh.
The neighborhood has been under rebel control for months.
The Observatory said troops also bombarded the town of Qalaat al-Madiq in Hama Province with mortar shells and heavy machine-gun fire. As has been true since the start of the conflict, activists’ reports are difficult to confirm since the country has severely restricted entry by foreign reporters.
Category: World News