General Election 2015: Ed Miliband will stab UK in the back just as he did to his brother David, warns Tory Defence Secretary Michael Fallon

Michael Fallon claims the Labour leader's 'lust for power' meant he was prepared to scrap Trident in exchange for SNP support in bizarre personal attack

Michael Fallon says Ed Miliband's willingness to betray his brother in his 'lust for power' was a sign of weakness (GETTY)

The Tories launched a highly personal attack on Ed Miliband this morning by claiming the Labour leader was prepared to “stab the United Kingdom in the back to become Prime Minister”.

Michael Fallon, the Defence Secretary, warned that his failure to commit to replacing all four of Britain’s nuclear submarines suggested he was prepared to scrap Trident in exchange for SNP support in a post-election deal.

Making a bizarre comparison to his decision to stand against his brother in the Labour leadership race in 2010, Mr Fallon said: “Ed Miliband stabbed his own brother in the back to become Labour leader. Now he is willing to stab the United Kingdom in the back to become prime minister.”

Britain's Defence Secretary Michael Fallon (Getty Images)

In a speech in London today, Mr Fallon will announce that the Conservatives will include a pledge in their manifesto to build a new fleet of four Trident submarines to replace the existing system and provide a continuous nuclear deterrent and will put pressure on Labour to match their plans.

But he claimed Mr Miliband’s willingness to betray his brother in his "lust for power" was a sign of his weakness and suggested he was prepared to do a deal with the SNP over Trident.

“We saw in that leadership election just what he would do to get into power. We saw what he did to his own brother. We need to know what he would do.

The memo, which has been rejected as “categorically, 100 per cent not true” also included a dismissal of Ed Miliband as not “PM material” (Getty)

"We can't be sure what kind of backstairs deal he is likely to do with the SNP... that is the uncertainty.

The Conservative party’s decision to make the attack so personal was a sign they were “desperate” and “rattled” and resembled the "politics of the gutter" Labour claimed, while even Tory commentators such as Tim Montgomery described Mr Fallon’s rhetoric as “embarrassing”.

Douglas Alexander said Labour's commitment to renewing Trident was 'crystal clear' (Getty) (Getty Images)

And Ken Livingstone, the former Labour Mayor of London, even suggested his party should use the country’s nuclear weapons to get revenge on Mr Fallon:

Douglas Alexander, shadow foreign secretary, insisted Labour’s support of renewing Trident was “crystal clear”.

"This is not up for negotiation with the SNP or with any other party. I don't know how I can say it plainer than that,” he told the Today programme.

"We are absolutely committed to a continuous at-sea deterrent. The Tories are like a wounded, cornered animal at the moment."

Nick Clegg also weighed in on the row, saying the modern nature of warfare meant we could downgrade our nuclear deterrent.

"I find it quite extraordinary that the Conservatives appear this morning to have elevated this nuclear weapons system as the most important thing they are in politics for and saying it's a red line.

"We think you can defend our country and maintain our nuclear deterrent without doing it in the all-singing, all-dancing way that the Labour and Conservative parties propose.”

Mr Fallon's sparked a lively reaction on Twitter from politicians, journalists and even Conservative commentators:

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