The US Secretary of State John Kerry said the continued violence in Syria showed that it was time for President Bashar al-Assad to go.
Speaking alongside Kerry, Foreign Secretary William Hague called for support for Syria's opposition to be increased significantly to bring the conflict to an end.
More top news
Cooler in the north, feeling close further south as moisture and heat build up
The first British boxer to win an Olympic gold medal beat Andre Dirrell in Boston last night to fight his way into the history books.
Louis Walsh reignites the flames of his row with by claiming she would refuse to be an X Factor judge if Nicole Scherzinger returns.