“The Syrian people are bleeding,” Ban told reporters after addressing the UN Security Council behind closed doors. “They are angry. They want peace and dignity. Above all, they all want action.”  

“The danger of a civil war is imminent and real,” he said, adding that “terrorists are exploiting the chaos.”  

Meanwhile UN observers are to make a fresh attempt on Friday to reach the village in Syria where the opposition said a massacre had taken place, a UN spokesman said.

A convoy of observers came under fire on Thursday, as they tried to get into Al-Qubair in central Hama province to verify reports of the killing of at least 80 people. A vehicle was damaged.

"The monitors will try again on Friday to enter Al-Qubair village," UN spokesman Hassan Siklawi told dpa.

Opposition activists blamed pro-government paramilitaries, known as Shabeeha, for the alleged massacre on Wednesday, saying women and children were among the dead.

The UN observers have been monitoring a shaky ceasefire in Syria, with their three-month mandate set to expire next month.

Activists on Friday reported heavy shelling by troops in the Al Khalidiyeh district in the central Homs province. They gave no casualty figures.

International envoy Kofi Annan is to meet US Secretary of State Hillary Rodham Clinton in Washington Friday.

Clinton's special adviser on Syria, Fred Hof, is meanwhile scheduled to hold talks with officials in Russia, Syria's ally.