DAMASCUS â€"  Government troops shelled residential areas in central Syria on Sunday, activists said, two days after the bombardment of a string of villages in the same region killed more than 90, many of them children.

Friday's assault on Houla, an area northwest of the central city of Homs, was one of the bloodiest single events in Syria's 15-month-old uprising. The U.N. said 32 of the dead were under the age of 10.

The attacks sparked outrage from American and other international leaders, and renewed concerns about the relevance of a month-old international peace plan that has not stopped almost daily violence.

Sunday's shelling hit neighborhoods in the central city of Hama and the rebel-held town of Rastan north of Homs, the Local Coordination Committees and the Britain-based Syrian Observatory for Human Rights said.

The two groups also reported clashes between troops and rebels in Hama, in the Damascus suburb of Harasta and in the capital's central Midan district. They said a bomb struck a security vehicle in the capital's upscale district of Mazzeh -- near a military airport, according to the LCC.

The Observatory said the vehicle bombing caused casualties but did not have other details on the dead or wounded from the day's violence.

A video posted online by activists showed thick black smoke billowing from what it said was Mazzeh.

Damascus is tightly controlled by regime forces but has been hit by a wave of blasts over recent months that claimed the lives of scores of people. Most of the blasts have targeted Syrian security agencies.

Outrage has mounted over the Houla deaths. U.N. observers, among more than 250 who were dispatched in recent weeks to salvage the cease-fire plan, found spent artillery and tank shells at the site Saturday. "Those who use violence for their own agenda will create more instability, more unpredictability and may lead the country to civil war," warned the observers' chief Maj. Gen. Robert Mood in a statement.

Kuwait, which currently heads the 22-member Cairo-based Arab League, announced it is making contacts for holding an Arab ministerial meeting that aims to "take steps to put an end to the oppressive practices against the Syrian people."

An unnamed foreign ministry official was quoted by Kuwait's official news agency, KUNA, as condemning the attack in Houla and blamed regime forces for the "ugly crime." The official said Kuwait is also make Arab and international contacts in order for the international community to "assume its responsibilities to stop the blood shedding of Syrian brothers."

The U.N. had denounced the attacks in a statement that appeared to hold President Bashar Assad's regime responsible, and the White House called the violence acts of "unspeakable and inhuman brutality." Syria blames armed "terrorist groups."

The bloodshed is yet another blow to the international peace plan brokered by U.N. envoy Kofi Annan and cast a pall over his coming visit to check on the plan's progress. The cease-fire between forces loyal to the regime of Assad and rebels seeking to topple it was supposed to start on April 12 but has never really taken hold, with new killings every day.

The U.N. put the death toll weeks ago at more than 9,000. Hundreds have been killed since.