Syrian troops storm into rebel city of Rastan

Hundreds of Syrian troops, supported by tanks and helicopters, stormed a key rebel city on Tuesday to crush armed opposition against Bashar al-Assad's regime.

Civilians in Rastan said at least 20 people were injured in the military operation, which began shortly before dawn and continued throughout much of the day, sending plumes of black smoke into the sky.

"Tanks closed in overnight and the sound of machine guns and explosions has been non-stop. They finally entered this morning," said Abu Qassem, a resident. As night fell, there was no definitive indication the army had succeeded in regaining control of the city, which lies north of Homs on the road to Turkey.

After six months of mostly peaceful protests against 41 years of Assad family rule, the opposition is turning violent, a development that could prove crucial.

The refusal of Tunisian and Egyptian commanders to confront non-violent demonstrations spelt the demise of their autocratic rulers.

The armed rebellion in Rastan is said to consist mostly of defecting soldiers. They have attacked army buses and roadblocks manned by troops and pro-Assad militiamen, known "shabiha", which have multiplied as the security forces have made a priority of extinguishing opposition in the city.

Meanwhile, residents in Homs claimed rebel soldiers hit a government tank with a rocket.

Opposition groups reported that hundreds of soldiers who have refused orders to fire on protesters have formed the Khalid bin al-Waleed battalion, named after the Arab conqueror of Roman Syria, in Rastan. The force reportedly possesses some tanks as well as light weaponry.

A video posted online on Tuesday by activists purportedly showed Youssef Hammoud, a captain in the Syrian army, flanked by several of his comrades, announcing his defection.

"We promise them that the town of Rastan will be their graveyard," he warned Mr Assad's army. "We promise them big surprises."

Another video, apparently filmed on Tuesday in Houla, a village across the Orontes river from Rastan, showed soldiers in fatigues among a crowd, chanting: "Freedom!"

"It's not surprising, given the level of violence over the past months, that we're now seeing members of the opposition begin to use violence against the military as an act of self-preservation," said Mark Toner, of the US State Department.

In all, gunfire and protests have been reported in six places in the past 48 hours, with reports that seven people were killed in Homs, including four soldiers trying to desert their ranks.

The United Nations has estimated that 2,700 civilians have been killed by the security forces since March.