Mood said he condemns “in the strongest possible terms the brutal tragedy” in Houla in the central province of Homs, adding that UN monitors visited the area and counted 92 bodies, including “more than 32 under the age of 10.”
“Those using violence for their own agendas will create more instability, more unpredictability and may lead the country to civil war,” Mood told reporters in Damascus, describing the violence as “indiscriminate and disproportionate.”
UN observers had rushed on Saturday to Houla after the reported massacre of scores of civilians there, amid renewed opposition calls for air strikes on regime forces.
The shelling of the town by regime forces began at around midday on Friday and continued until dawn on Saturday, the Syrian Observatory for Human Rights said, giving a death toll of more than 90.
State media blamed “armed terrorist gangs” for the violence.
“The circumstances that led to these tragic killings are still unclear,” said Mood. “Whoever started, whoever responded and whoever carried out this deplorable act of violence should be held responsible.”
Confirming the use of artillery and tank shells in the Houla killings, Mood also called “on the Syrian government to cease the use of heavy weapons and to all parties to cease violence in all its forms.”
But the rebel Free Syrian Army said on Saturday it could no longer commit to the ceasefire brokered by UN-Arab League envoy Kofi Annan, unless there was an immediate solution to regime violence.
“We announce that unless the UN Security Council takes urgent steps for the protection of civilians, Annan’s plan is going to go to hell,” an FSA statement said.
Earlier, the opposition Syrian National Council urged the UN Security Council to act urgently, while the Syrian Observatory accused the Arab and international communities of being “complicit” in the killing.