Senior Conservatives campaigning to Leave the European Union are planning "a very British coup" to unseat David Cameron and George Osborne in the event of a Brexit vote, according to former Scottish first minister Alex Salmond.

George Osborne's political career "is virtually over" regardless of the outcome of EU referendum after he alienated scores of Tory MPs with his proposal to slash public spending and increase taxes to tackle a predicted £30 billion post-Brexit "black hole", the SNP MP said.

Mr Salmond said Iain Duncan Smith, Michael Gove and Boris Johnson are already preparing "an alternative government" in the event of a Leave vote on June 23.

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Speaking on LBC Radio, Mr Salmond said: "I deplore the way that George Osborne conducts the campaign, but his wasn't the only emergency Budget being put forward today.

"There was a six-point plan from the Brexiteers. They put forward a plan, not just for the campaign. This was a plan for an alternative government.

"If you believe that Iain Duncan Smith, Michael Gove and Boris Johnson aren't going to be even more right-wing than even the present extreme right government, then you don't know them as well as I do.

"So, put not your faith in the ringleaders of the Brexiteers - the people who are performing, right now, a very British coup."

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He added: "The gang, if you like, the Goves, IDS, Boris Johnson, one or all of them will be part of a new Tory government which will go through a Tory leadership election and they will then have to command a majority.

"I think it is a very fair point that there will be an economic hit.

"Therefore, you cannot imagine, given that these people have all got a track record of calling for rigorous austerity budgets, you would find it difficult to believe that one of these people - Chris Grayling perhaps could be the next chancellor - will not come in on a platform of fiscal rectitude responding to the economic shock.

"The problem with George Osborne is that he's not the one that would be delivering that Budget. He'll be offski. He'll be off to a seat in the city, but which city I don't know."

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Mr Salmond agreed that, whatever the result of the referendum, "George Osborne's political career is virtually over" after his Budget warning.

He said: "He is now unelectable. He was to be Cameron's chosen successor. That was the line of succession.

"So, let's say it's a Brexit vote, I think Cameron and Osborne are out the next day.

"It it's a Remain vote, I can see Cameron getting some leeway because he has won a close-run thing, but Osborne has pretty much poisoned the well with a large number of Conservative MPs.

"As soon as he said I'm having this emergency scary Budget, 57 Tory MPs have signed saying we're not going to support it, which is quite impressive organisation."