DAMASCUS, June 16: Escalating violence in Syria forced United Nations observers to suspend operations on Saturday, in the clearest sign yet that a peace plan brokered by international mediator Kofi Annan has collapsed.

Chief monitor General Robert Mood said the fighting posed a threat to his unarmed observers, one of whose patrols was fired upon four days ago, and prevented them from carrying out their mandate to oversee Annan’s widely-ignored April 12 ceasefire.

The Norwegian peacekeeper blamed both government troops and anti-regime activists for the relentless conflict, in which President Bashar al-Assad’s forces are trying to crush an increasingly well-armed insurgency which grew out of a 15-month-old wave of protests.

“There has been an intensification of armed violence across Syria over the past 10 days,” Gen Mood said.

“The lack of willingness by the parties to seek a peaceful transition, and the push towards advancing military positions is increasing the losses on both sides.”

Diplomats say Gen Mood is expected to brief the United Nations Security Council on Monday or Tuesday about the unrest in Syria, which the head of UN peacekeeping said this week was in the throes of full-scale civil war.

The United States said it was consulting with international partners on “next steps” and called on Syrian authorities to uphold commitments to Annan’s peace plan “including the full implementation of a ceasefire”.

Despite their criticism of Assad, Washington and its western allies have shown no appetite for a Libya-style military intervention, while veto-wielding UN Security Council members Russia and China have shielded Damascus from UN sanctions.

US President Barack Obama will hold talks with Russian President Vladimir Putin on Monday on the sidelines of a G20 summit in Mexico, but expectations are low for any progress to break their deadlock on Syria.

Gen Mood said the violence posed “significant risks” to the 300 unarmed members of the UN Supervision Mission in Syria (UNSMIS), who have been operating there since late April.

“In this high-risk situation, UNSMIS is suspending its activities. UN observers will not be conducting patrols and will stay in their locations until further notice,” Gen Mood said, noting the decision would be reviewed on a daily basis.

Last Tuesday shots were fired at a car carrying UN observers who were turned away from the town of Haffeh by angry Assad supporters throwing stones and metal rods at their convoy.

Three UN cars were also damaged in May when they were caught up in an attack that killed 21 civilians in Khan Sheikhoun.

Syria’s Foreign Ministry said it had been informed of Gen Mood’s decision on Friday evening and told him it understood his concern for the safety of the monitors, blaming the attacks on activists fighting government forces.

Many hundreds of people, including civilians, rebels and government forces, have been killed in the two months since Annan’s ceasefire deal was supposed to come into effect.

But the violence has increased sharply this month, with anti-regime activists formally abandoning any commitment to Annan’s ceasefire and government forces using attack helicopters and artillery to pound opposition strongholds into submission.

The pro-opposition Syrian Observatory for Human Rights said at least 28 civilians were killed on Saturday, most of them in army shelling on the eastern suburbs of Damascus.

In a sign that government forces were also suffering heavy losses, SANA reported on Saturday military funerals for 24 soldiers and members of security forces.—Reuters