United Nations Secretary General Ban Ki-moon and UN-Arab League envoy Kofi Annan issued a joint statement on Saturday condemning the massacre of 92 people, reportedly carried out by Syrian government forces a day earlier in the Houla area of central Homs province.

"This appalling and brutal crime involving indiscriminate and disproportionate use of force is a flagrant violation of international law and of the commitments of the Syrian government to cease the use of heavy weapons in population centers and violence in all its forms," they said.

"Those responsible for perpetrating this crime must be held to account," they added, demanding that Syrian President Bashar al-Assad immediately halt all violence.

UN observers, who were sent to the country to monitor adherence to a UN-brokered cease-fire, confirmed on Saturday that more than a third of the dead were children.

In a statement, the head of the observer mission, Major General Robert Mood, also confirmed claims that artillery tank shells had been used in the offensive, which was one of the worst in Syria's nearly 15-month uprising.

'Terrorist gangs' responsible

According to anti-regime activists more than 100 people were killed on Friday night after heavy shelling on the area by Syrian troops.

Amateur videos posted on YouTube, apparently from Houla, showed horrifying images of children lying dead on a floor. The sound of wailing could be heard in the background.

Syrian state television aired some of the footage on their websites, saying victims had been killed by "terrorist" gangs.

ccp/ncy (AFP, Reuters, AP)