The danger of civil war in Syria is "imminent and real", the UN's chief has said, as tensions rise over the latest alleged massacre by government forces.
Ban Ki-Moon told reporters the country can "quickly go from tipping point to breaking point" and made a fresh appeal for calm on all sides following the atrocity, which is said to have claimed at least 78 lives.
"The Syrian people are bleeding," he said after addressing the UN Security Council behind closed doors.
"They are angry. They want peace and dignity. Above all they want action."
UN-Arab League envoy Kofi Annan said during the same news conference he was holding talks on bringing key world and regional powers into a contact group on the crisis.
"There are discussions going on about setting up such a group," he said.
Mr Ban earlier told the UN General Assembly that President Bashar al Assad had "lost all legitimacy" and said he wanted a "new level" of international action to halt the bloodshed in Syria.
Monitors have been unable to verify reports of the massacre in the province of Hama because they are being stopped at army checkpoints, the head of the UN mission in Syria said earlier.
General Robert Mood said a team was sent to the village of Mazraat al Qubeir to investigate claims that forces loyal to Mr Assad had killed dozens of people, including women and children.
The team will attempt to gain access again on Friday.
If reports of the slaughter are accurate, it will rank among the worst atrocities in Syria's 15-month uprising.
Mousab Alhamadee, an activist based in Hama, said women and children "were burned inside their homes".
But Syrian authorities have denied carrying out any massacre in Hama province, with state TV instead claiming troops found nine bodies after attacking a terrorist stronghold.