Syrian troops backed by tanks and artillery advanced in the city of Rastan, near Homs, on Saturday after four days of clashes with army defectors, activists said.
"The city is almost destroyed from the shelling of the army," an anti-government activist who lives in Lebanon said.
"So far we have 10 army defectors killed and a number were wounded," he said.
Syrian exiles said there were about 2,000 defectors in the city.
Government troops have been fighting army defectors in Rastan in the first prolonged armed confrontation since protests erupted against Assad six months ago.
Rastan has become a redoubt for soldiers who have refused orders to fire on pro-democracy protesters. The city, with a population of 60,000, is near the western provincial capital of Homs.
Tens of thousands of protesters took to the streets across Syria on Friday demanding the removal of President Bashar Assad, as fighting continued between loyalist forces and insurgents in the centre of the country, according to activists.
Colonel Riad al-Assaad, a high-ranking defector told Reuters on Friday that more than 10,000 soldiers have deserted the Syrian army and defectors are attacking security police who enforce loyalty to President Bashar Assad.
Guerrilla-style attacks were concentrating on Military and Air Force Intelligence, secret police personnel entrusted with preventing mutiny in the military, who have been behind some of the biggest attacks on pro-democracy protesters, Colonel al-Assaad told Reuters.
Foreign journalists are barred from Syria, where the regime has killed an estimated 2,700 people during a crackdown on pro-democracy protesters, according to opposition activists and rights groups.
Earlier this week, European UN Security Council members softened a draft resolution condemning Syria's six-month crackdown on anti-government protests, but Russia said on Thursday that it could not support the new text.
The four European members of the council had hoped to put the draft resolution to a vote on Friday. The United States is expected to support it, envoys said, despite its disappointment about compromises made in an attempt to woo Russia, China, Brazil, India and South Africa - the "BRICS" nations.
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