At least 90 people were killed in Syria when government forces attacked protesters in the area of Houla in the central Homs province, an activist group reported on Saturday.

According to the Syrian Observatory for Human Rights, 25 children were among the dead and 100 more were injured in army shelling of the town on Friday. Syrian troops were also said to have pounded the area, made up of several towns and villages, using tanks, mortars and heavy machine guns.

"It was a real massacre that took place and the UN observers are just staying silent," the head of the human rights group, Rami Abdel Rahman, told news agency AFP.

If the figures are correct, Friday's death toll will have been of the highest in one specific area since a UN-brokered ceasefire came into effect last month.

Clashes were also reported in the northern city of Aleppo on Friday, where Syrian troops fired tear gas and live ammunition at thousands of protesters gathered to demonstrate against the rule of President Bashar al-Assad. The London-based Observatory said five people were shot dead by security forces, including a 12-year-old boy.

'Unacceptable violence'

In a report to the United Nations Security Council on Friday, Secretary General Ban Ki-moon condemned the Syrian regime's continued violation of the cease-fire, which forms part of a UN-backed peace plan.

Ban accused the Syrian regime of perpetrating "unacceptable levels of violence" in a "stepped-up security crackdown." He said it had led to "massive human rights violations."

The UN chief added that there had only been "small progress" in the implementation of the plan, which was brokered by international envoy Kofi Annan.

A spokesman for Annan said on Friday that the envoy was making plans to return to Syria early next week. It will be his first trip to the country since presenting the plan, which stipulates that UN observer teams monitor the regime's adherence to the April 12 cease-fire.

According to the Syrian Observatory for Human Rights, more than 12,600 people have been killed in Syria in the 14-month-long revolt against Assad's rule, including nearly 1,500 since the UN truce came into effect.

ccp,slk/ng (AFP, AP, Reuters)