The United Nations Security Council has blamed the Syrian government for attacking residential areas of the town of Houla with artillery and tank shelling - but avoided saying who was responsible for the massacre of more than 100 men, women and children.
In a press statement after an emergency meeting on Sunday night, the council said the "outrageous use of force" against civilians violated international law and Syrian government commitments under previous UN resolutions to stop all violence, including the use of heavy weapons in populated areas.
It said "those responsible for acts of violence must be held accountable".
It demanded that the Syrian government immediately halt the use of heavy weapons and pull its troops out of cities and towns and asked UN secretary general Ban Ki-moon and the world body's observer mission in Syria to continue investigating the attacks in Houla.
Britain and France had proposed issuing a press statement condemning the attack on civilians and pointing the finger at the Syrian government for Friday's massacre. But Russia called for an emergency council meeting, saying it first wanted a briefing by General Robert Mood, the head of the unarmed UN observer mission.
Russia, which considers Syria its closest Middle East ally, has used its security council veto power to block resolutions raising the possibility of UN action against President Bashar Assad.
The assault on Houla was one of the bloodiest single events in Syria's 15-month uprising against Assad's regime.
Gen Mood told the closed-door council session that UN observers, after revisiting the scene, had raised the death toll in Houla to 108 people, UN peacekeeping chief Herve Ladsous said outside the council chamber. Those killed included 49 children and 34 women, Ahmad Fawzi, a spokesman for international envoy Kofi Annan, said. Gen Mood said on Saturday that observers confirmed from an examination of ordnance found at the scene that artillery and tank shells were fired.
The council statement "condemned in the strongest possible terms the killings, confirmed by United Nations observers, of dozens of men, women and children and the wounding of hundreds more in the village of Houla, near Homs, in attacks that involved a series of government artillery and tank shellings on a residential neighbourhood".
It also "condemned the killing of civilians by shooting at close range and by severe physical abuse", but avoided assessing responsibility for the killings. The council asked Mr Ban and the observer mission to investigate the attacks and report back.