Britain 'perfectly entitled' to demand new EU terms - Cameron

"What's happening in Europe right now is massive change being driven by the existence of the euro. The countries of the euro, they have got to change to make their currency work", he said.

He added that: "As they need to change, what that means is they are changing the nature of the organisation to which we belong. And thus we are perfectly entitled – and not just entitled but actually enabled, because they need changes – to ask for some changes ourselves."

Cameron is preparing the ground for a major speech setting out his negotiating strategy later in January. Although the Prime Minister is anxious to avoid a straight 'in/out' referendum on EU membership, he has come under pressure from his Conservative party prompted by rising euroscepticism following the financial crisis as well a rise in support for the UK Independence party. Recent opinion polls indicate that Britons favour leaving the EU by a 51-40 margin.

In recent months he has consistently maintained that any talks to revise the EU treaties to increase the integration of the eurozone could be used to re-write Britain's terms of membership.

However, Nick Clegg, Cameron's Deputy and the leader of the Tories' coalition partners, the traditionally pro-European Liberal Democrats, opposes a referendum.

Meanwhile, former cabinet minister and EU Trade Commissioner Peter Mandelson described Cameron's tactics as "economic insanity" in a column in the Guardian.

"The signal it sends to the world is that we are on our way out of the European single market and that those who invest in Britain in order to trade in that market should think again," he said.

Although Britain has the power to block any treaty reforms for the eurozone, any changes to its own status would also require the approval of 26 other member states. Cameron's demands are likely to include exemptions for the City of London from EU financial regulation and an opt-out from social policy legislation.

In December 2011 the Tory leader exasperated other leaders by refusing to allow them to incorporate the Berlin-inspired fiscal compact treaty within the EU treaties after failing to win the promise of concessions for the City of London.

But although Britain's tactics have angered some other member states, it continues to have allies. Germany pointedly did not let London be isolated in recent EU budget negotiations.

For his part, European Council President Herman van Rompuy told the UK press that leaving the bloc would be like watching "a friend walking off into the desert".

Cameron has already made it clear that Britain will not sign up to the proposed banking union legislation. In October his Home Secretary, Theresa May, announced that Britain would exercise its right under the Lisbon Treaty to opt-out of EU justice and home affairs legislation.