Labour's leadership contest has seen a generation's work in moving the party to the centre of British politics "unravelled in the space of 12 months", Chancellor George Osborne has claimed.

In an interview published on the eve of the close of voting, Mr Osborne said the policies of likely victor Jeremy Corbyn represented "a real risk to Britain's security" and that his success had dragged leadership rivals Andy Burnham and Yvette Cooper to the left in the course of the contest.

The Chancellor - widely regarded as the most likely Conservative leader at the 2020 general election - made clear that "Blairite" Liz Kendall was the candidate most feared by Tories.

"There's no doubt that Liz Kendall's ideas would have caused ... the greatest problems," Mr Osborne told the New Statesman magazine.

"Some of the arguments Tristram Hunt makes, or Chuka Umunna - those ideas are clearly the ones that would most challenge the Conservative Party, because they attempt to occupy the centre of politics. Corbyn wants to vacate the centre and ignore those voices."

Mr Osborne said he had "looked on in complete astonishment" during the contest to choose a successor to Ed Miliband as "the whole of the Labour Party moves leftwards, abandoning the centre, and I think therefore abandoning the working people of this country".

He told the New Statesman: "I can't help noticing that, for most of my childhood and early adult life, a succession of Labour Party leaders reformed the constitution of the Labour Party - Neil Kinnock did, John Smith did, Tony Blair did - to make sure that it was more rooted in what the British people wanted.

"And it does seem, as an external observer, that a generation's work has been unravelled in the space of 12 months."

On Mr Corbyn's policy agenda, the Chancellor said: "There's no doubt ideas like abandoning Britain's nuclear deterrent at a time when, frankly, more and more countries are trying to acquire nuclear weapons, or some of the things that have been said about terrorist organisations like Hamas, are deeply unpalatable.

"I don't think they represent the views of the British people. But we don't regard what is being said in the Labour leadership contest as a joke. We take it deadly seriously. I regard these things as a real risk to Britain's security were they ever to have the chance to be put into practice."

Mr Osborne added: "I don't think that's particularly good for the country that you have an opposition heading off to the wilderness.

"But I think now there's a big responsibility for the Conservative Party to hold to the centre, to represent working people, to continue these reforms that previously have had cross-party support. And you know what? I can say it's the Conservative Party that is looking forward, not back."