ABOUT 220 Syrians, mostly civilians, were been killed in a village in the rebellious Hama region when it was bombarded by helicopter gunships and tanks then stormed by militiamen who slaughtered families, opposition sources have said.

UN special envoy Kofi Annan said he was shocked and appalled by news of intense fighting, significant casualties, and the confirmed use of heavy weaponry such as artillery, tanks and helicopters in the village of Tremseh.

"I condemn these atrocities in the strongest possible terms," Mr Annan said in a statement.

There were no independent accounts of the number of dead or how they were killed. UN monitors in Syria are confined to Damascus because of mounting violence.

An activist video – the only film to appear so far – showed the bloodied corpses of 15 young men. Most wore T-shirts and jeans.

Syrian state television said there had been fighting in Tremseh and accused "armed terrorist groups" of committing a massacre there, but gave no death toll. It said three soldiers had been killed.

Opposition reports also said rebels of the Free Syrian Army had been killed in a battle. Lieutenant Ibrahim Zuait al Tarkawai was among rebels who died "defending the people of Tremseh", the Hama Revolution Leadership Council said.

"We can verify continuous fighting yesterday in the area of Tremseh," said UN monitoring mission chief General Robert Mood. "This involved mechanised units, indirect fire, as well as helicopters," he said. UN monitors were ready to go in and seek verification of facts if and when there is a credible ceasefire, he said.

If scores of civilians were killed, this could be the worst atrocity in 16 months of fighting between rebels and the forces of President Bashar al-Assad. World powers are deadlocked over how to halt the bloodshed, with Russia and China opposed to Western and Arab calls for Assad to step down.

Activists said the killing took place on Thursday, as the UN Security Council began negotiating a potentially crucial new resolution on Syria. Washington said it showed the need to move to tougher action, but Russia again ruled out such a step.

"More than 220 people fell today in Tremseh. They died from bombardment by tanks and helicopters, artillery shelling and summary executions," the Revolution Leadership Council of Hama said in a statement.

The Sunni Muslim village, surrounded by farmland near the Orontes River, was first shelled then invaded by pro-government Alawite militiamen who swept in and killed victims one by one, it said. Some civilians were killed while trying to flee.

Armed Assad loyalists known as Shabbiha have been accused repeatedly of cold-blooded, indiscriminate killings carried out on the coattails of army offensives into rebel-held districts.

A local activist in Tremseh named Ahmed said there were 60 bodies at the mosque.

He added: "There are more bodies in the fields, bodies in the rivers and in houses ... people were trying to flee from the time the shelling started and whole families were killed trying to escape."