The UN Security Council has unanimously adopted a resolution that authorizes an initial deployment of up to 300 unarmed military observers to Syria for three months to monitor a fragile week-old ceasefire in the country's 13-month old conflict.

The Russian and European drafted resolution said that deployment of the UN observer mission, which will be called UNSMIS, will be "subject to assessment by the Secretary-General [Ban Ki-moon] of relevant developments on the ground, including the cessation of violence".

Saturday's resolution also noted that the cessation of violence by the government and opposition is "clearly incomplete".

It authorizes the UN mission for an initial 90 days to monitor the cessation of violence and monitor and support implementation of UN-Arab League envoy Kofi Annan's six-point peace plan.

Ban will make the "assessment" on whether it is safe to deploy the mission. This would include the consolidation of the cessation of violence started on April 12.

There is no threat of sanctions in the resolution but the council said it will assess the implementation of the mission and "consider further steps as appropriate".

Bashar Ja'afari, the Syrian ambassador to the UN, said his government has already implemented all its responsibilities in the Annan peace plan.

"It continues to assist the special envoy. And daily it is undertaking measures to underscore this, including the release of detainees who were not responsible for terrorist crimes and the delivery of humanitarian aid to the affected region in co-operation with OCHA."

Russia's UN Ambassador Vitaly Churkin welcomed the resolution's adoption.

"We now see the main aim as being the unswerving clear respect by all parties of the provisions of the resolution," he told the council. "Any deviation in terms of interpretation, or deviation from the provisions is unacceptable."

French Ambassador Gerard Araud said "we're taking a risk" with the deployment of UNSMIS, adding that the council would have to consider sanctions if the Syrian government continues the violence.

Homs visit

Earlier on Saturday, the Syrian authorities allowed a small advance team of UN ceasefire monitors to enter the battered city of Homs after resident opposition activists said shelling and gunfire stopped for the first time in weeks.

A UN spokesman said that the team toured the city and met with its governor.

"They are now visiting districts of the city," Khaled al-Masri said. Syria's state news agency SANA confirmed the statement.

Activists in Homs said that the shelling of the city only ceased to make it look as if the government was abiding by the truce, mediated by peace envoy Annan.

They said that shelling would resume as soon after the monitors left.

"It is very clear that the Syrian government can stop the violence whenever it wants at anytime in the country," Walid al-Fares of the Homs Revolution Council said.

"There is no shelling whatsoever," Fares told Al Jazeera, a day after activists had reported the deaths of at least 12 people there amid continued shelling by government forces on several neighborhoods.

"We believe that the calmness has to do with the arrival of the observers. We wish they could live with us so that this peace can remain."

Ban has said helicopters and other military hardware would be needed by the monitors, but Syria has dismissed any need for UN aircraft.

The team has visited several restive areas including the southern province of Daraa and some of the suburbs of the capital Damascus.

Reports of violence

Syrian activists said that columns of smoke rose from the Mezze military airport in Damascus after hearing a huge explosion in the area. The blast was followed by heavy gunfire inside the airport.

Activists reported that security forces closed Sumaria road near the airport and blocked access to and from the capital, as police vehicles were seen rushing towards the fighting.

Mezze military airport hosts air force and defense divisions and an intelligence brigade.

In the southern province of Deraa, the Local Co-ordination Committees. an opposition activist network, said loud explosions were heard in al-Karak al-Sharqi area while the town of Mseifra was being raided.

Meanwhile, the state news agency on Saturday said that an "armed terrorist" group blew up an oil pipeline in the eastern province of Deir al-Zor, near the border with Iraq.

"An armed terrorist group detonated an improvised explosive device on a oil line near Abu Hammam, in the province of Deir al-Zor, which led to a fire," SANA said, giving no more details.

At least 34 people were reported killed by activists across the country on Friday amid mass anti-government protests after noon prayers.

The UN advance team did not did not venture out on Friday, the day when anti-government protests are usually held after noon prayers, in a blow to protesters' hopes.

Colonel Ahmed Himiche, the team's head, said they did not go out "because we don't want to be used as a tool for escalating the situation".

PHOTO CAPTION

Moroccan Colonel Ahmed Himmiche (L) leader of the first U.N. monitoring team in Syria, arrives back at a hotel in Damascus after returning with his team from a visit to Homs city where there are protests against the regime of Syrian President Bashar al-Assad April 21, 2012.

Aljazeera