The UN Security Council has condemned "in the strongest possible terms'' the Syrian government for the Houla massacre in which at least 108 people were killed.
A statement agreed by the 15-nation council, including Syrian ally Russia, said the attacks "involved a series of government artillery and tank shellings on a residential neighborhood'' and again demanded that President Bashar al-Assad withdraw heavy weapons from Syrian towns.
"The members of the Security Council reiterated that all violence in all its forms by all parties must cease. Those responsible for acts of violence must be held accountable,'' said the statement.
The death toll was today revised upwards to 108 from an initial reported 90, and revealed via video-link by the head of the UN monitoring team in Syria, Major General Robert Mood.
The Houla killings on Friday and Saturday sparked international outrage and condemnation, but Russia's deputy ambassador to the UN had cast doubt on the guilt of Syria's government over the massacre.
Mood, a Norwegian, briefed the Security Council as UN and Arab League peace envoy Kofi Annan was expected to fly to Damascus tomorrow to try to rescue his six-point peace plan amid a crumbling ineffective truce.
The regime was "not at all'' to blame for the massacre in Houla in central Homs province, Syrian foreign ministry spokesman Jihad al-Makdissi insisted.
Britain and France had proposed a statement condemning the massacre, but diplomats said Russia would not agree to the condemnation until the briefing by Mood.
Mood said there were signs of tank shelling, mortar fire and "physical abuse,'' and said the deaths were from "shrapnel'' and gunfire at "point-blank'' range, diplomats at the closed-door meeting at the United Nations said.
UN observers had initially counted 92 dead in Houla, 32 of them children.
UN peacekeeping chief Herve Ladsous later told reporters the death toll of 108 was the "estimate'' of the UN Supervision Mission in Syria (UNSMIS).
The incident was one of the bloodiest episodes since Assad's regime launched a brutal crackdown on opponents in March last year that has left thousands dead.
"The investigation indicates that first there was the artillery barrage and then militia fighters moved into Houla,'' a UN source told AFP.
Blaming "terrorists'' for the killings on Friday and Saturday, Makdissi said Damascus had opened an investigation, with results expected within three days.
"Not one Syrian tank went in,'' he said.
Makdissi said Annan was expected in Damascus on Monday, although there was no confirmation from the former UN chief's spokesman.
In Istanbul, exiled opposition head Burhan Ghalioun on Sunday called for a "battle of liberation and dignity'' against the regime until the United Nations takes action under Chapter VII allowing military intervention.
And the rebel Free Syrian Army (FSA) warned that unless the international community took concrete action it would no longer be bound by Annan's UN-backed peace plan and his April 12 ceasefire which has been violated daily.
Mood warned Saturday of "civil war'' after his observers visited Houla.
He also called on the Syrian government to "cease the use of heavy weapons, and on all parties to cease violence in all its forms.''
``Those using violence for their own agendas will create more instability, more unpredictability and may lead the country to civil war,'' Mood warned.
Amid mounting calls for world action to halt the bloodshed, UN Secretary General Ban Ki-moon joined the chorus of international condemnation of the carnage.
"This appalling and brutal crime, involving indiscriminate and disproportionate use of force, is a flagrant violation of international law,'' a UN spokesman quoted Ban and Annan as saying.
Condemnation also poured in from the United States, Britain, France and Germany, with French Foreign Minister Laurent Fabius saying he was making "immediate arrangements'' for a meeting of the Friends of Syria group that backs the opposition.
Arab League foreign ministers are also to hold an emergency meeting, the bloc's current president Kuwait said.
Despite the outcry, violence raged on, according to the London-based Syrian Observatory for Human Rights, which reported at least 33 people killed across the country on Sunday, among them 24 civilians.
At least nine civilians died in the central city of Hama, where regime mortar and heavy machine gun fire also wounded more than 150 people, some of them critically, the group said.
Thousands of people also protested nationwide against the Houla killings, and in the capital Damascus, one demonstrator was shot dead by security forces, the Observatory said.