Clashes flared across Syria yesterday, opposition activists said, a day after the UN Security Council had called on all sides to stop fighting and seek a negotiated settlement to the year-long uprising.

UN Secretary-General Ban Ki-moon said the council's unanimous statement had sent a clear message to Syria to end all violence, but the appeal had little impact on the ground, where rebels were seeking to oust President Bashar al Assad.

Opposition sources said Syrian tanks had heavily shelled a large neighbourhood in the city of Hama yesterday after fighting between Free Syrian Army rebels and pro-Assad forces.

The shelling destroyed houses in the Arbaeen neighbourhood of northeast Hama, which has been a centre of revolt. Opposition sources said at least 20 people had been killed in army attacks there in the last two days.

It is impossible to verify reports from Syria because authorities have denied access to independent journalists.

The British-based Syrian Observatory for Human Rights (SOHR) reported heavy fighting in al Qusair, a town close to the Lebanese border. Three residents died in the fighting and four soldiers were killed when rebels ambushed their checkpoint.

Syrian troops also attempted to storm the northern town of Sermeen, killing two people and wounding dozens, SOHR said, quoting its network of contacts within Syria.

"Syrian forces are still not able to get inside the town because of fighting, but they are shelling Sermeen and using heavy machine guns," said SOHR head Rami Abdelrahman.

Fighting also erupted in southern Deraa, where several soldiers died in an ambush, he said, while President Assad's forces conducted raids in the eastern province of Deir al Zor and coastal Latakia province to try to snuff out rebel fighters.