British Prime Minister David Cameron broke new ground on Europe by suggesting British withdrawal from the EU is "imaginable", aligning himself with the fiercely Eurosceptic Boris Johnson, The Guardian reports.

The PM stressed that he supported membership of a reformed EU, though he said Britain was "in charge of our own destiny".

The remarks by the prime minister echoed comments at the weekend by Johnson, who has criticised Cameron and George Osborne for supporting moves towards greater political and economic integration in the eurozone. The London mayor told The Andrew Marr Show on BBC1 that it would not be the "end of the world" if Britain left the EU, though that was not his preferred option.

Johnson said he would like a referendum to be held before the next general election, which is due to take place in 2015, on the "single market and a withdrawal from a lot of the nonsensical policies".

In a statement to MPs on Monday on last week's EU summit, Cameron ruled out "an immediate in/out referendum".

Cameron wants to move at a slow pace because he believes major revisions to the Lisbon treaty are unlikely to take place until after the German elections next year.