Prime Minister David Cameron said on Friday the crisis in the euro zone raised doubts about the future of Europe's single currency and that his priority was shielding the UK economy from the fall-out.

Cameron also said he did not want to repeat an annual battle with banks over bonuses, saying they should rein in payments and support businesses at a time of slowing growth.

It's a very difficult time for the euro zone ... There is real turbulence in the markets, real question marks over whether countries can deal with their debts and a big question mark over the future of the euro zone, he said in an interview on BBC Radio 2.

Reform of the 17-nation currency bloc is on the agenda after market turmoil spread from Greece to much larger Italy.

Cameron has repeatedly said that euro zone countries need to become more integrated. Britain is not a member of the single currency and Cameron ultimately wants to claw back some powers from the larger European Union.

My responsibility is of course to try and help bring about a solution to those problems, he added.

But above all my priority has got to be to help keep the economy safe and to make sure, if we are going to face a difficult time ... to try and come through the storm.

Britain is preparing contingency measures to cope with the fallout from the euro zone crisis and Business Secretary Vince Cable has said it is better placed than before the 2008/09 financial crisis.

Cameron was questioned about whether the turmoil in Europe, Britain's biggest trading partner, would drive the UK back into recession.

In the last quarter of the economy we did grow, we grew by 0.5 percent -- others are forecasting growth -- but it's clearly slowing growth and it's a difficult time for the economy.

The prime minister said he did not want to spend the next six months battling with banks about annual bonuses. He warned that the government would speak out if it was unhappy with proposed payments at RBS in which it has an 83 percent stake after a bailout.

What we've done with the bankers is we've said 'right, you are going to pay the bank levy', which is 2.5 billion pounds every year, there are going to be tougher controls on bonuses, there is going to be more transparency.

But let's be frank -- we've got to have an economy in which the banks are lending money.

Many small firms say they are still struggling to get enough support from banks.

(Reporting by Keith Weir and Stefano Ambrogi; Editing by Catherine Evans)