Foreign Secretary William Hague has welcomed unanimous United Nations Security Council backing for deployment of military observers to monitor the ceasefire in Syria as a "vital step".
An advance team of 30 is set to leave for the conflict zone amid reports that renewed shelling in the city of Homs and elsewhere is putting the fragile cessation of hostilities at risk.
Russia, which has vetoed two previous resolutions, approved the text which said both sides should "cease all armed violence in all its forms".
The resolution also called on the government of president Bashar Assad to implement the peace plan devised by former UN secretary general Kofi Annan which includes the withdrawal of troops.
"I welcome the United Nations Security Council's unanimous endorsement of a rapid deployment monitoring mission for Syria," Mr Hague said following the vote in New York.
"This mission is a vital step in supporting the fragile ceasefire in Syria. It is essential that it begins its work urgently and without impediment.
"I urge all parties to maintain the ceasefire to allow the monitoring mission to deploy and complete its task."
He urged the Syrian regime to ensure the observers enjoyed free movement, access and communications and said both sides should guarantee their security without hampering the mission.
"These conditions are set out in today's UN Security Council resolution, and we will hold the Syrian regime to it and to Kofi Annan's six-point plan," Mr Hague said.
"It must stop troop movements towards population centres, end the use of heavy weapons in civilian areas and withdraw the military to their barracks.
"Failure to do these things will result in further international pressure on the Assad regime and steps to ensure that they are held to account."