The Syrian government has denied its troops massacred at least 92 people, about one-third of them children, Friday in the town of Houla.

Foreign Ministry Spokesman Jihad Makdissi called accusations against the Syrian government a “tsunami of lies”. Instead, he blamed heavily armed “terrorists” who he claimed attacked soldiers.

U.N. observers said artillery and tanks were used to pound Houla, located northwest of the central city of Homs.

Makdissi said Syrian soldiers retaliated to defend their positions, but he denied they had used artillery and tanks.

The Houla massacre marked the deadliest single attack since Syria's anti-government uprising began about 15 months ago.

Arab and western governments have issued statements expressing outrage and hinting that President Bashar al-Assad's government is to blame.

The latest violence has further raised questions about the effectiveness of an April cease-fire agreement between anti-government rebels and the Syrian government.

The rebel Free Syrian Army warned that it will not adhere to the U.N.-mediated peace plan if the international community does not take concrete actions to protect citizens.

Makdissi called the Houla assault “brutal” and said the Syrian government has launched an investigation.

Syrian troops shelled residential areas Sunday in the central city of Hama, and the rebel-held town of Rastan.

The Syrian government says U.N.-Arab League envoy Kofi Annan, who mediated the peace plan, is expected in Syria on Monday.

The United Nations says more than 10,000 people have been killed in Syria since the government began its crackdown on dissent in March 2011.