A convoy of UN observers was pelted with stones by unidentified group of people near a suburban area of Syria's capital Damascus Friday, witnesses told Xinhua, amid reports of unabated violence elsewhere.

The convoy was pelted with stones while heading to the suburb of Dumair, northeast to Damascus, before it reached a military checkpoint at the entrance of Dumair, witnesses said, adding that one of the UN vehicles was slightly damaged with smashed window.

However, none of the observers were injured.

Last Wednesday, a roadside bomb ripped through the UN convoy while it was en route to southern Daraa province, injuring eight members of the accompanying security forces.

The head of the rebel Free Syrian Army has recently said that UN observers have become "perjurers," and added that his forces will not stay calm for long. He claimed that the failure of the UN mission would positively reverberate on the welfare of rebels, "as some countries have progressive attitudes toward arming the rebels. "

The Syrian conflict has become more militarized as protesters and army defectors are taking up arms to defend themselves against the "bloody crackdown" of government troops.

Earlier Friday, anti-regime protests erupted in several Syrian cities, hailing the armed rebels and urging people to take up arms.

An amateur footage uploaded onto YouTube pictured people in Daraa held banners that urged people to arm themselves.

The armed rebels deem the armed resistance as the sole way to topple the tough regime of Syrian President Bashar al-Assad, who has managed to keep his feet on the ground despite the wearing 14- month unrest.

Assad seems to still have a firm grip on power, in part because he still enjoys the backing of the moneyed classes in Damascus and Aleppo, Syria's main powerhouses, and also because the majority of the army is ranking behind him despite reports of defection.

Meanwhile, UN observes' spokesman said Friday that 150 observers are now on ground in Syria, 105 of whom are unarmed military monitors.

The observers arrived in Syria last month to monitor the implementation of six-point plan brokered by UN-Arab League joint special envoy Kofi Annan, which has called mainly to halt violence from all sides to pave the way for a political settlement to Syria 's crisis.

The mission has so far done little to stem the violence, as bombings, kidnappings and killings are reported on daily bases.

On Thursday, two suicide bombers blew themselves up before an intelligence complex in Damascus, leaving scenes of destruction and more than 55 people, mostly civilians, killed.

Witnesses told Xinhua that the blast sent the bodies of civilians hurtling in the air like toys. No one claimed responsibility for the attack. However, previous suicide bombings had been claimed responsibility by an al Qaida-inspired group known as the al-Nusra Front to Protect the Levant.

Earlier on Friday, Syrian authorities killed a suicide bomber in northern Aleppo province when he was trying to detonate his booby-trapped minibus at al-Sha'ar district.

Sources said that a group of UN monitors visited the site and examined the explosive-laden vehicle, which has been loaded with 1, 400 kg of explosives.

Military sources said that had the car exploded, hundreds of people would have been killed.

Also Friday, four army personnel were killed by armed groups, when their vehicle came under fire near the central Homs province.

On the opposition side, the Britain-based Syrian Observatory for Human Rights said that 10 people have been killed Friday in several areas across Syria, while the Local Coordination Committees, another activists' network, put the number at 13.

The activists' account is impossible to be independently checked.

The Syrian Opposition blames the government for the daily grind of violence.