Tony Blair today claimed euroscepticism is like a ‘virus’ which has spread through the Conservative party.

The former Prime Minister said the Tory ‘has got it really bad’ as he warned of the dangers of abandoning Brussels.

In a major speech in central London, Mr Blair admitted Britain could survive outside the European Union but warned David Cameron it would be ‘a monumental error of statesmanship’ to turn his back on the EU.

With Europe still in the grip of a crisis, and ‘fundamental, far reaching reform’ required, Britain should not be heading for the exit.

Mr Blair said: ‘This is the last moment, the last moment conceivable, that we should start talking about leaving, about quitting the field just as the game starts, marginalising ourselves at the very point at which we should be at the centre of things.

‘Europe is a destiny we will never embrace easily. But it is an absolutely essential part of our nation remaining a world power, politically and economically.

‘It would be a monumental error of statesmanship to turn our back on it and fall away from a crucial position of power and influence in the 21st Century,’ he told a business audience at foreign affairs thinktank Chatham House in London.

He added: 'All my life I've fought ideology on the left. The right have got it really bad on this Europe thing. It's a virus.'

Mr Cameron is under growing pressure from Tory MPs to adopt a more Eurosceptic stance, having suffered an embarrassing rebellion when dozens of backbenchers demanded a cut in the EU budget.
David Cameron last week told journalists a deal on the EU budget had not been reached at a summit in Brussels

There is growing speculation that Ed Miliband may be considering committing Labour to an in/out poll, Mr Blair said it was not ‘sensible’ to be talking about a referendum at this point.

The Prime Minister has ruled out an in-out referendum, but has proposed a renegotiation to bring back powers from Brussels which would then be put to the British people in a vote.