UN observers in Syria visited on Saturday the central village of Treimsa, where more than 150 people were killed this week, according to a spokeswoman for the UN mission and an activist on the ground.
The activist in Hama province, going under the name Abu Ghazi, said the observers had met residents of the village and "inspected places that were bombed and where there were traces of blood."
The UN spokeswoman, Sausan Ghosheh, confirmed that a group of observers had entered Treimsa.
"They entered Treimsa. The convoy is around 11 vehicles in total," she told AFP.
"We were informed yesterday that there was a ceasefire. So we sent a patrol to Treimsa on a reconnaissance mission. The patrol assessed the situation, ie if there was in fact a ceasefire and our access to the town," she said, adding that the patrol would seek "verification of the facts."
The Treimsa killings have triggered a global outcry against the regime of President Bashar al-Assad, with UN chief Ban Ki-moon calling for urgent action to stop the bloodshed.
The head of Syrian Observatory for Human Rights, Rami Abdel Rahman, told AFP it "might be the biggest massacre committed in Syria since the start of the revolution" against Assad in March 2011.
If confirmed, the 150-person toll would exceed that of a massacre at Houla on May 25, when a pro-Assad militia and government forces were accused of killing at least 108 people.
A spokesman for Syria's military said the army killed "many terrorists" in Treimsa, but no civilians, in a "special operation... targeting armed terrorist groups and their leadership hide-outs."