DAMASCUS - Outbursts of fighting threatened to undermine a fragile ceasefire that took effect in Syria on Friday after President Bashar al-Assad’s regime and the main rebel force agreed to down arms for a four-day Eidul Azha holiday.

But the violence was still at unusually low levels even though the ceasefire had “collapsed” in several regions of the country, said the Syrian Observatory for Human Rights. And there were no indications from either the Assad regime or the main rebel Free Syrian Army (FSA) that they were abandoning the truce. “The ceasefire has collapsed in several regions of Syria but there is still less violence and fewer victims than usual,” Observatory director Rami Abdel Rahman told AFP.

He said fighting took place in various parts of the country, including in and around the capital Damascus, in the second city Aleppo, in the central city of Homs and near the Wadi Deif military base in the northwest.

By late afternoon, the monitoring group said, 23 people had died so far in violence, including 10 soldiers and four rebels in the fighting at Wadi Deif, instead of the dozens killed across the country in past days. On Thursday, at least 135 people were killed, the Observatory said, including 65 civilians, 41 soldiers and 29 rebels. Regime forces and the FSA said Thursday they would follow UN-Arab League peace envoy Lakhdar Brahimi’s call for the temporary ceasefire, but both reserved the right to respond to any aggression.

If the ceasefire holds it would be the first real breakthrough in halting - even temporarily - the violence that has plagued Syria during the 19-month conflict which monitors say has killed more than 35,000 people.

The international community has piled pressure on all sides to stand by the truce and a senior Arab League official said Friday it appeared to be holding. Ahmed Ben Hilli, the League’s deputy secretary general, told AFP the truce was “being respected according to initial indications” and that it could be followed by a longer ceasefire and a proposal to deploy UN peacekeepers. After clashes on Thursday night, the ceasefire took hold with morning prayers kicking off the Eidul Azha feast at the end of the hajj pilgrimage, and state television showed Assad attending a Damascus mosque, smiling and chatting with worshippers.

The ceasefire was also tested as security forces opened fire at anti-regime protests that followed the prayers across the country.

The protests took place in Damascus and its suburbs, in Aleppo, in the northeast in Deir Ezzor and Raqa and at several towns in the southern Daraa province, according to activists and the Observatory. At the town of Inkhel in Daraa, police used gunfire to disperse protesters, injuring three people, said the Observatory, which relies on a network of activists, medics and lawyers on the ground for its information.

General Mustafa al-Sheikh of the FSA said the rebels considered the protest crackdown a violation of the ceasefire but were not planning to respond.

“Preventing demonstrations by opening fire is a violation of the ceasefire. But we are showing more restraint than the regime because for the moment we want to give the ceasefire a chance,” he told AFP by telephone from Turkey.

In Aleppo, residents said they were taking little joy in the Eid holiday despite the lull in the fighting.

“Although there was no gunfire this morning, there was nothing that made it feel like Eid today,” said Hany, 35, a restaurant owner in the central district of Azizia.

The city’s streets were largely empty amid sporadic rebel attacks and with residents unable to move freely because of army checkpoints, an AFP correspondent said.

A soldier in the Old City of Aleppo said he would have to stay on guard. “I heard about the ceasefire on television but my duty is to stay alert to stop the rebels from moving forward,” he said.

The Syrian uprising began in March 2011 as a peaceful reform movement inspired by the Arab Spring but steadily militarised after being met with brutal state repression.

The ceasefire was backed this week by the United Nations Security Council and a spokesman for UN chief Ban Ki-moon said Thursday that “the world is now watching” to ensure both sides stick by their commitment. The United States also expressed hope the ceasefire will be respected.

“What we are hoping and expecting is that they will not just talk the talk of ceasefire, but that they will walk the walk, beginning with the regime,” US State Department spokeswoman Victoria Nuland said.

The Syrian army said it would cease military operations from Friday morning to Monday, but warned it would react if “armed terrorist groups” carry out attacks or reinforce their positions, or if fighters cross into the country.

An April ceasefire announced by Brahimi’s predecessor, former UN secretary general Kofi Annan, failed to take hold.

Brahimi has stressed the importance of even a temporary lull in the fighting, saying: “If we succeed with this modest initiative, a longer ceasefire can be built” that would allow the launch of a political process.