George Osborne pleaded with David Cameron not to hold an in/out referendum on the European Union, it emerged last night.

Senior Tory sources revealed the Chancellor had repeatedly warned against the move in the run-up to the Prime Minister’s referendum pledge in 2013.

Meanwhile a major new biography of Mr Cameron said the issue had opened up a ‘rare schism’ between the two men.

George Osborne (left) pleaded with David Cameron (right) not to hold an in/out referendum on the European Union, it emerged last night

The revelation that the Chancellor tried to block the referendum will raise eyebrows among Eurosceptic Tories, given his role as Mr Cameron’s lead negotiator in talks to secure a new deal with the EU.

A spokesman for the Chancellor last night said it was ‘nonsense’ to suggest he had ever opposed holding an in/out vote.

But several Tory sources told the Daily Mail that he campaigned behind the scenes against the idea.

He is said to have warned Mr Cameron that a referendum would not resolve the tensions within the Tory party over the issue, and risked an accidental British exit from the EU.

He also warned that holding an in/out vote risked putting the Conservatives on the wrong side of mainstream business opinion, handing a political gift to Labour.

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One source claimed Mr Osborne – along with former chancellor Kenneth Clarke and Justice Secretary Michael Gove – continued to lobby the Prime Minister to reject a referendum until days before he made the landmark pledge at the offices of the Bloomberg news agency in January 2013.

‘Osborne absolutely did not want to have this referendum,’ the source said. ‘He thought it would be a disaster, and would only provide a temporary get-out from the pressure over Europe.

‘Gove was also concerned and went to see Osborne to tell him to stop it happening, but it was too late, the decision was made.’

Another source confirmed that the Chancellor intervened with Mr Cameron over the issue, but suggested he ‘did not push it’ after being told a referendum was definitely on the cards.

‘He certainly expressed his opinion to Cameron that a referendum was not a good move,’ the source said. ‘But [William] Hague and Ed Llewellyn [the Downing Street chief of staff] thought it had to be done.’

The accounts are backed up by a new biography of Mr Cameron, which says the EU issue opened up a ‘rare schism’ between the Prime Minister and his Chancellor. Anthony Seldon, author of Cameron at 10, writes: ‘Both men are profoundly irritated by their Eurosceptic MPs, but Osborne is even more pragmatic than Cameron. The Chancellor’s view is that it is simply not sensible to talk about disengaging from major international institutions in the 21st century – not worth considering it.

‘Osborne’s eye is on a further horizon ... his own leadership succession. Business opinion weighs heavily on him, and he is loath to make the Conservative Party appear the riskier proposition to business than Labour.’

A spokesman for the Chancellor said yesterday: ‘This is nonsense. The Chancellor believes that the British people should be given the chance to decide whether or not we stay in a reformed EU.

‘Alongside the Prime Minister, he is working to negotiate a package of reforms ... that can be put to the British people in 2017.’

One source claimed Mr Osborne – along with former chancellor Kenneth Clarke (left) and Justice Secretary Michael Gove(right) – continued to lobby the Prime Minister to reject a referendum until days before he made the landmark pledge at the offices of the Bloomberg news agency in January 2013