An agreement to begin a ceasefire in Syria within a week is an "important step" to ending the civil war in the country, Foreign Secretary Philip Hammond has said.
Diplomats meeting at a summit in Munich agreed to implement "cessation of hostilities" in Syria, US secretary of state John Kerry announced.
Mr Hammond welcomed the settlement but warned it would succeed onlyif Russia ceased bombing moderate opposition groups.
Mr Hammond said: "The International Syria Support Group (ISSG) meeting in Munich committed members to achieving a cessation of hostilities within a week, to delivering humanitarian assistance to named besieged communities by this weekend and to facilitating rapid progress in negotiations aimed at political transition.
"If implemented fully and properly by every ISSG member, this will be an important step towards relieving the killing and suffering in Syria. But it will only succeed if there is a major change of behaviour by the Syrian regime and its supporters.
"Russia, in particular, claims to be attacking terrorist groups and yet consistently bombs non-extremist groups including civilians. If this agreement is to work, this bombing will have to stop: no cessation of hostilities will last if moderate opposition groups continue to be targeted."