05/09/2012 07:40 EDT | Updated 07/09/2012 05:12 EDT

Syrian bombs, shelling threaten peace plan

Syrian rebels killed at least seven militiamen loyal to President Bashar al-Assad in an attack on a bus travelling through a Damascus suburb, opposition activists say.

The attack with rocket-propelled grenades destroyed the vehicle on the edge of Irbin, five kilometres east of the capital's main Abbasid Square, at about 9:30 a.m. local time (1:30 a.m. ET), Reuters reported.

Earlier, a roadside bomb struck a Syrian military truck, wounding six soldiers just seconds after a convoy carrying the head of the UN observer mission passed by.

An Associated Press reporter who was travelling in the UN convoy said the explosion blew out the military truck's windows and caused a plume of thick, black smoke. The UN convoy was not hit.

"We were driving behind the UN convoy as protection when a roadside bomb exploded, wounding a first lieutenant and five troops," a soldier who asked to be identified only by his first name, Yahya, told The Associated Press at the scene.

At least three bloodied soldiers were rushed away.

On Tuesday, UN special envoy Kofi Annan gave a bleak assessment of his month-old peace plan for Syria, saying violence remains at "unacceptable levels."

CBC Radio's Laura Lynch visited Homs and Khalidiya on Tuesday, reporting that Homs was devastated but calm, while fighting continued in Khalidiya.

Still, Annan's peace plan and the presence of monitors are offering some remaining hope.

"A lot of people say that the presence of the UN monitors has led to a reduction in violence, and in exchanges of gunfire and in shelling," she told World Report. "For most people, they believe that it is really still the last best chance to avoid this going into a much wider conflict."

The roadside blast went off after the head of the UN observer mission, Maj. Gen. Robert Mood, headed into the Daraa area with a team of observers and a convoy of journalists. The explosion occurred more than 100 metres behind the convoy.

It wasn't clear who was behind the blast.

Demands for defence

Syria's rebel leader, Col. Riad al-Assad, threatened to resume attacks because the government has not honoured a ceasefire, the London-based Asharq al-Awsat newspaper reported Wednesday. Assad told the paper that "our people are demanding that we defend them."

The comments were published in Wednesday's edition of the paper and could deal yet another blow to a peace plan brokered by special envoy Kofi Annan.

"There is a profound concern that the country could otherwise descend into full civil war and the implications of that are frightening," Annan told reporters in Geneva after briefing a closed-door session of the UN Security Council in New York by videoconference.

The observer mission, he said, "is the only remaining chance to stabilize the country."

Although the death toll rises daily, the UN has ruled out any military intervention of the type that helped bring down Libya's Moammar Gadhafi, in part out of fears that it could make the conflict worse.