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
Thousands of pounds worth of heroin has been found stashed inside the covers of children's books at Heathrow Airport.
Internet search engine says Cilla Black was the subject of more online searches than Kim Kardashian this year, beaten only by Taylor Swift.
A supermarket price war and fierce competition across the rest of the high street has seen shop prices slumped by a record level last month.