Almost 100 Conservative MPs this week wrote to Mr Cameron demanding a legal commitment to hold a referendum on Britain’s relationship with the EU after the next election. Several ministers privately believe that leaving the union should not be ruled out.

Mr Cameron did not rule out some sort of vote on European issues eventually, but insisted that he would not give the British people the option of leaving the EU outright.

"I completely understand why some people want an in/out referendum, why they wanted it yesterday, why they want it today,” he said.

"Some people just want to get out: I completely understand that but I don't share that view, I don't think that's the right thing to do.”

More than 3 million British jobs depend on access to the EU’s single market, he said. As “massive trading nation”, the UK economy benefits from membership.

The Brussels summit saw the 17 eurozone nations take further steps to integrate their economies, outlining plans for common regulation of their banks. During the talks, the UK defeated a European Commission plan for the new rules to apply to all banks across the EU.

The emergence of a more integrated eurozone bloc within the EU has raised fears that British influence will decline and free-market rules will be reversed.

"Europe is changing. That change has consequences for Britain,” Mr Cameron admitted.

“My job is to make sure we secure all the safeguards that we need so that our role in the EU, our access to the single market, our say in the single market, is properly safeguarded.”

The new “banking union” and other changes made to save the single currency could require changes to the EU treaties or a whole new treaty. Government sources believe that could give Britain a veto and the opportunity to bargain to win back powers for Britain.

"This is going to be an unfolding story but one where I think Britain has every chance of securing the sort of relationship that we want in Europe," Mr Cameron said.

"For those of us who are practical Eurosceptics, who know there is a real benefit from being engaged but are frustrated by some of the ways the relationship works, I see lots of reasons to say the argument is going in our direction," he said.