Britain will not accept the European single market being discussed by any group other than the full 27 members of the European Union, Prime Minister David Cameron said on Friday.

Why are we in the organisation (European Union)? We're there because we're a trading nation, and we want access to the single market and a full say about the rules of the single market, Cameron told BBC Radio 4.

What we can't have is the single market being discussed outside the European Union, and we'll do everything possible to make sure that doesn't happen, he added.

Cameron's comments come amid fears that groups within the EU that do not include Britain could decide new rules affecting the single market as they try to ease the eurozone debt crisis.

Britain was left isolated in December when Cameron refused to sign up to a new EU treaty to tackle the crisis.

The prime minister also hailed what he said was a big fall in bonuses to bankers and other professionals, which have stoked public anger at a time of deep government spending cuts.

There's been a massive reduction in the level of bonuses compared with three or four years ago .... and we want to see that trend continue.

(Reporting by Mohammed Abbas; editing by Keith Weir)