The anti-government Free Syrian Army has ordered its fighters to stop offensive operations pending a meeting with Arab League delegates monitoring President Bashar Al-Assad's compliance with a peace plan, the rebels' commander said.

Colonel Riad Al-Asaad said his forces had so far been unable to talk to the monitors, in the first week of their month-long mission, and he was still trying to contact them urgently.

"I issued an order to stop all operations from the day the committee entered Syria last Friday. All operations against the regime are to be stopped except in a situation of self defence," he told Reuters.

"We have tried to communicate with them and we requested a meeting with the team. So far there hasn't been any success. We haven't been given any of the (phone) numbers for the monitors, which we have requested. No one has contacted us either."

How widely Turkey-based al-Asaad's order is heeded by anti-government gunmen inside Syria is in question. A video shot by rebel fighters this week showed the ambush of a convoy of army buses in which, activists said, four soldiers were killed.

Assad has signed up to an Arab League plan for a verifiable withdrawal of his heavy weaponry and army from turbulent Syrian cities where more than 5,000 people have been killed since March, many shot during peaceful anti-government protests but also many killed in rebel attacks and defence actions.

The Arab League mission has met with strong scepticism from the outset, over its makeup, its small numbers, its reliance on Syrian government logistics and an initial assessment by its Sudanese chief that the situation was "reassuring".

That comment was met with disbelief in the West on Wednesday but on Friday, Syria's ally Russia accepted the judgement.

"Judging by the public statements made by the chief of the mission M. Al-Dabi, who in the first of his visits went to the city of Homs ... the situation seems to be reassuring," the Russian Foreign Ministry said on its website.

Sudan's General Mustafa al-Dabi, who some link to war crimes in Darfur in the 1990s, visited the flashpoint city of Homs briefly on Tuesday and said he saw "nothing frightening".

Activist video from Homs over the months has depicted a trail of death and destruction sowed by the military, with hundreds of killings of civilians reported.

The British Observatory for Human Rights, an opposition activist network, said protests broke out on Friday in several areas of the country, including a large gathering of 70,000 in the Damascus suburb of Douma, where monitors were present.

Pro-Assad demonstrations were also reported.

The Observatory said Syrian forces killed four people, including two defectors, in an ambush in Talkalakh near Lebanon's border.

"Unfortunately, reports show that the violence has continued in Syria over the past few days," Britain's Minister for the Middle East and North Africa, Alistair Burt, said in a statement.

"I urge the Syrian government to meet fully its obligations to the Arab League, including immediately ending the repression and withdrawing security forces from cities. The Syrian government must allow the Arab League mission independent and unrestricted access ..." Burt said.

In Brussels, a spokesperson for European Union foreign policy chief Catherine Ashton said the EU also "urges Syria to comply with the Action plan of the Arab league in all its components" including "an immediate end of violence, the release of political prisoners, pulling the military out of cities". – Reuters