International mediator Kofi Annan said on Sunday that the UN Security Council's decision to deploy a further 300 ceasefire monitors in Syria marked a "pivotal moment for the stabilisation of the country".

In a statement issued in Geneva, he called on both Syrian government forces and opposition fighters to put down their weapons and work with the unarmed observers to consolidate the fragile ceasefire that took effect 10 days ago.

"The government in particular must desist from the use of heavy weapons and, as it has committed, withdraw such weapons and armed units from population centres and implement fully its commitments under the six-point plan," Annan said, referring to his plan accepted by both sides to end 13 months of violence.

The Security Council unanimously adopted a Russia-European drafted resolution on Saturday that authorises an initial deployment of up to 300 unarmed military observers to Syria for three months, to be known as UNSMIS.

A handful of monitors have already been deployed for the past week as part of an advance team and went to the flashpoint city of Homs on Saturday after months of bombardment.

"The work of the Mission should help create the conditions conducive to launching the much-needed political process, which would address the legitimate concerns and aspirations of the Syrian people," Annan said.

"I call on the government and the opposition and all the people of Syria to prepare to engage in such a process as a matter of utmost priority," he added. - Reuters