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,” Annan said.
There were no independent accounts of the number of dead or how they were killed. UN monitors in Syria are currently confined to Damascus because of mounting violence.
An activist video, the only film record to appear so far, showed the bloodied corpses of 15 young men with faces or shirts drenched in blood. 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 immediately.
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. Some civilians were killed while trying to flee, it said.
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.
Fadi Sameh, an opposition activist from Tremseh, said he left the town before the reported killing spree but was in touch with residents. “It appears that Alawite militiamen from surrounding villages descended on Tremseh after its rebel defenders pulled out, and started killing the people. Whole houses have been destroyed and burned from the shelling.
“Every family in the town seems to have members killed. We have names of men, women and children from countless families,” he said. Many bodies were taken to a local mosque, he added.
According to a detailed account by activists, a convoy of 25 vehicles with army and security forces headed west after dawn on Thursday, with three armoured vehicles and five trucks towing artillery, passing through the town of Muharda in the direction of the village of Tremseh.
“They blockaded the village from all four sides and began violently and randomly firing on houses as a helicopter flew overhead. As the attack happened the electricity and telephone lines were cut. Residents gathered in the streets in a state of fear and panic. They were unable to flee because of the blockade from every side,” the report posted on activist websites said.