Syria has agreed to admit a UN team of experts to examine conditions for a possible observer mission in the violence-swept country, the foreign ministry spokesman said on Saturday.

"Regarding the plan of (international peace envoy) Kofi Annan, the major next step will be the signing of the protocol addressing the question of observers," Jihad Makdisi said, quoted by the official SANA news agency.

"Syria will soon welcome an ad hoc delegation to negotiate the mechanism of its (deployment)," he added, without specifying dates.

UN officials said on Friday that the world body is making plans for at least 250 observers to be sent to Syria if the government halts its offensive on protesters and gives its agreement for the international force.

Damascus has accepted Annan's six-point peace plan, which calls for a commitment by all parties to cease all armed violence, under UN supervision, while claiming success in halting the attacks carried out by "terrorist groups."

At present the plan would be for the observers to be unarmed but under the protection of Syrian government forces, according to one senior diplomat at the United Nations.

The observers would mostly come from UN missions in Lebanon (UNIFIL), the Golan Heights between Syria and Israel (UNDORF) and in South Sudan (UNMISS), the diplomat added.

A senior UN official said that for the mission to go ahead there needed to be a Security Council mandate, as well as a ceasefire and the agreement of the host country.

Annan already dispatched a team of experts to Damascus earlier this month, where they held three days of intensive talks with Syrian authorities on "urgent steps" to implement his proposals on halting the violence.