- The British foreign minister will meet his Russian counterpart over Syria on Monday
- Images from the massacre show bodies of mangled children, some with skulls cracked
- The Syrian regime denies involvement in the bloodbath
- Some Security Council members point to "government artillery and tank shelling"
(CNN) -- International envoy Kofi Annan is expected to visit Syria on Monday, even though rebel leaders say his peace plan is "dead" following a gruesome massacre that killed 108 people in one town.
Meanwhile, British Foreign Secretary William Hague is expected to meet with Russian Foreign Minister Sergey Lavrov on Monday as Syrian rebels beg U.N. Security Council members for airstrikes against regime forces.
The U.N. council's attempts to formally condemn the Syrian regime have been repeatedly blocked by Russia and China.
U.N. monitors in Syria said 49 children were among the 108 people slaughtered Friday in Houla, a suburb of the anti-government bastion of Homs.
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Can violence in Syria be stopped? Since then, overwhelming grief has washed over Houla as opposition activists and residents blame President Bashar al-Assad's regime for the bloodshed.
"By God, I washed the dead bodies of nine children. One was less than nine months old!" a man screamed to a U.N. observer. "Why are they treating us like animals? We are humans. Did the infant carry an RPG? Was he a fighter? It was a baby, he had a pacifier in his mouth."
Images from Houla show a room crammed with the mangled and bloody bodies of children -- some with their skulls torn open.
The Houla massacre reignited international fury against al-Assad's regime for its 14-month crackdown on dissidents seeking an end to his rule.
On Sunday, some U.N. Security Council members condemned the Houla attacks "that involved a series of government artillery and tank shellings on a residential neighborhood" as well as the killings of civilians by close-range gunshots.
"Such outrageous use of force against the civilian population constitutes a violation of applicable international law," Azerbaijan's deputy ambassador Tofig Musayev said.
U.S. National Security Council spokesman Tommy Vietor said the United States was horrified by "credible reports" of the massacre, "including stabbing and ax attacks on women and children."
But the Syrian government denied involvement in the Houla deaths, with officials blaming regional and Western "enemies" for the massacre.
Bashar Jaafari, Syria's U.N. ambassador, called the deaths "an appalling, horrific unjustified and unjustifiable crime" and said the Syrian government had launched a national commission to investigate.
But to some, the investigation was a farce.
"There's no way a Syrian military commission can credibly investigate this horrendous crime when so much evidence suggests pro-government forces were responsible," said Sarah Leah Whitson, Middle East and North Africa director at Human Rights Watch. "Annan should insist that Syria grant access to the U.N. commission of inquiry to investigate this and other grave crimes."
U.N. Security Council attempts to formally condemn the Syrian regime have been repeatedly blocked by Russia and China.
Prior to his meeting in Moscow on Monday, Hague expressed hope that Russia would pressure the Syrian government to abide by Annan's peace plan, which calls for a cessation of violence.
"We have had many differences of view with Russia at the Security Council, but Russia does support the Annan plan," the British foreign secretary said in a statement. "And so I hope Russia will redouble its efforts to get the Assad regime to implement that plan."
But over the weekend, members of the rebel Free Syrian Army said the Annan plan is "dead" after the Houla massacre.
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Syrian strife breeds unrest in Lebanon "The joint command of the FSA inside Syria announces that it is no longer possible to abide by the peace plan brokered by Kofi Annan, (which) the regime is taking advantage of in order to commit more massacres against our unarmed civilians," Free Syrian Army spokesman Col. Qasim Saad Eddine said in a video posted Saturday.
"This is a clear evidence that Kofi Annan's plan is dead and a clear indication that Bashar Assad and his criminal gang do not understand anything but the language of force and violence," Eddine said. He urged the U.N. Security Council to "issue urgent and swift resolutions to save Syria, its people and the entire region by forming an international coalition mandated by the UNSC to launch airstrikes" against regime forces and their strategic points.
U.N. officials say more than 9,000 people, mostly civilians, have died and tens of thousands have been uprooted since the Syrian crisis began in March 2011. Opposition groups report a death toll of more than 11,000 people.
CNN cannot independently confirm details from Syria nor the authenticity of videos, as the Syrian government strictly limits access by foreign journalists.
CNN's Saad Abedine, Mohammed Jamjoom and Holly Yan contributed to this report.
