LONDON — European nations are discussing whether to overturn an arms embargo on Syria and are seeking to press Arab countries and the United States for a new impetus to end the deadly 20-month conflict, Britain’s foreign policy chief said Friday.

British Foreign Secretary William Hague met in London with Mouaz al-Khatib, head of the new Syrian National Coalition for Opposition and Revolutionary Forces, but said the UK would not yet join France in officially recognizing the opposition group as the representative of Syria’s people.