United Nations monitors have been shot at while trying to get to the scene of the latest Syrian massacre, secretary-general Ban Ki-moon said.
The UN chief told the General Assembly that the unarmed observers were initially denied access to the scene in central Hama and "were shot at with small arms" while trying to get there. He did not mention any casualties.
Mr Ban condemned "this unspeakable barbarity", saying that each day in Syria sees more "grim atrocities" and adding that for many months it has been evident that president Bashar Assad and his government "have lost all legitimacy".
Earlier monitoring team chief General Robert Mood said some UN patrols were also stopped by civilians in the area and that observers were informed by residents that their safety would be at risk if they entered Mazraat al-Qubair in central Hama province.
Syrian opposition groups say pro-government militiamen killed dozens of people, including women and children, in Mazraat al-Qubair, with some stabbed to death and others burned.
The Britain-based Observatory for Human Rights said dozens were killed, and the Local Co-ordination Committees group said more than 78 people died, including many women and children. It said pro-government militiamen known as shabiha first shelled the farming area and then went in and killed the residents.
Syria's main opposition group in exile, the Syrian National Council, also said 78 people were killed. It said 35 were from the same family and more than half were women and children. It said the militiamen converged on Qubair from neighbouring pro-regime villages. It said some of the dead were killed execution-style, and others were attacked with knives.
The violence comes on the heels of a horrific massacre in late May in Houla, a cluster of villages in central Homs province, which left more than 100 dead including many children and women gunned down in their homes.
UN investigators blamed pro-government gunmen for at least some of those killings but the Syrian regime denied responsibility and blamed rebels for the deaths.
US secretary of state Hillary Clinton condemned the Syrian government for "simply unconscionable" violence, accusing president Bashar Assad of intensifying a crackdown that has already killed thousands.