Syria on Thursday blamed up to 800 rebel fighters for the massacre last week in Houla that killed more than 100 people, nearly half of them children.
The government's report on its investigation into the deaths starkly contradicted accounts of witnesses who blamed "shabiha" or the shadowy gunmen who operate on behalf of President Bashar Assad's regime. The United Nations also said it had strong suspicions that those pro-regime gunmen were responsible for much of the carnage last Friday.
Susan E. Rice, U.S. ambassador to the United Nations, dismissed the Syrian investigation's conclusion as "another blatant lie," telling reporters in New York that "there is no factual evidence that would substantiate that rendition of events."
She said the Geneva-based U.N. Human Rights Council is discussing a resolution that would establish an independent investigation to ensure that facts are established so the perpetrators can be prosecuted.
At Thursday's news conference, Qassem Jamal Suleiman, who headed the government's investigation into the massacre, categorically denied any regime role. He said hundreds of rebel gunmen carried out the massacre after launching a coordinated attack on five security checkpoints.
The aim, he said, was to frame the government and to ignite sectarian strife in Syria.
"Government forces did not enter the area where the massacre occurred, not before the massacre and not after it," he said, adding that the victims were families who refused to oppose the government or carry arms.
A Houla-based opposition activist said it was clear that there had been no government investigation. "The regime is looking for ways to justify the massacre to the world," said Saria al-Houlany. "It's clear that there wasn't any professional probe. If we had 800 fighters in Houla, this massacre would not have happened."
The Houla massacre was one of the deadliest incidents since the uprising against Assad's regime started in March last year. Activists say that about 13,000 have been killed in 15 months.
U.N. Secretary-General Ban Ki-moon called on Syria to stop the bloodshed and warned of a protracted conflict.
Nearly 300 U.N. observers have been deployed around Syria to monitor a cease-fire that was supposed to go into effect April 12 as part of a peace plan negotiated by international envoy Kofi Annan. But the plan has unraveled, and the images from the Houla massacre caused outrage to spike.
"The massacre of civilians of the sort seen last weekend could plunge Syria into a catastrophic civil war -- a civil war from which the country would never recover," Ban said in Istanbul.
He added that the international community was united in demands that the Syrian government act on its responsibilities to its people.
"We are there to record violations and to speak out so that the perpetrators of crimes may be held to account," Ban told a summit of the Alliance of Civilizations. "Let me state plainly, however: The U.N. did not deploy in Syria just to bear witness to the slaughter of innocents," he added. "We are not there to play the role of passive observer to unspeakable atrocities."