A government spokesman blamed al-Qaida for the killings in the city of Houla, which included a number of children.
"We deny that the Syrian armed forces were responsible for what took place in Houla," said Foreign Ministry spokesman Jihad Makdissi.
"There is no armed opposition in Syria," Makdissi said. "There is either an intellectual opposition, and we welcome their participation in national dialogue, or there are armed terrorist gangs that refuse the political resolution."
Makdissi pointed the finger at the United States, Turkey and other perceived enemies of Syria for being behind al-Qaida's reputed campaign of violence. CNN said the statements came as unsubstantiated video of the scene in Houla began appearing on Youtube.
Rebel leaders said the massacre was squarely the doing of the Syrian security forces and proved the United Nations cease-fire in Syria was useless.
The United Nations said that while Damascus denied it had sent armor and troops into Houla, they did bombard the rebel-controlled village with artillery. Witnesses said the barrage was followed up by an assault by army infantry and pro-government gunmen.
The United Nations and the United States issued strong condemnations of the attack while rebel groups vowed to avenge the massacre, The New York Times said.
"Those who perpetrated this atrocity must be identified and held to account," U.S. Secretary of State Hillary Clinton said in a written statement. "The United States will work with the international community to intensify our pressure on [President Bashar] Assad and his cronies, whose rule by murder and fear must come to an end."
Other international leaders called for emergency meetings of the U.N. Security Council, the Arab League and the informal 80-nation Friends of Syria coalition.
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