CAIRO: A ceasefire in Syria appeared to be holding and may eventually allow the deployment of peacekeepers, a senior Arab League official said on Friday, hours after the truce began.

Ahmed Ben Hilli, the deputy secretary general of the Arab League, told AFP the truce brokered by UN and Arab League envoy Lakhdar Brahimi was "being respected according to initial indications".

He said the truce, partly aimed at allowing relief groups to reach isolated areas stricken by the conflict, could be followed by a longer ceasefire and a proposal to deploy UN peacekeepers.

"There could be a longer ceasefire, and a mechanism like peacekeeper forces from the United Nations. This is one of the main ideas being proposed" by Brahimi, he said.

His remarks came before the fragile ceasefire was shaken by isolated outbursts of violence at Harasta near the capital Damascus and around the Wadi Deif military base in the northwestern province of Idlib.

The Syrian Observatory for Human Rights said security forces also fired at demonstrators, but the regime and main rebels groups have not indicated they would abandon the truce.

"Violent clashes started around 10:30 am (0730 GMT) around the Wadi Deif base. The army responded by bombing the neighbouring village of Deir Sharqi. It is the first violation of the ceasefire," the Observatory's Rami Abdul Rahman told AFP.

He said that among the rebels at the battle were members of the Islamist Al-Nusra Front, which said it would not respect the truce between President Bashar al-Assad's regime and the main rebel Free Syrian Army group.

The conflict pitting mostly Sunni rebels against Assad's minority Alawite-led regime began with protests in March 2011 that gave way to a civil war that has killed more than 35,000 people, according the Observatory.