Michael Portillo was last night battling to persuade Tory MPs he did not betray William Hague as they prepared to decide his political future.

The shadow chancellor and his supporters were aiming to limit any damage caused by the screening of video diaries compiled during the General Election campaign by the Tory leader's then press secretary, Amanda Platell.

She alleged in last night's Channel 4 programme that Mr Portillo's aides knifed Mr Hague in the back at the height of the election.

Her claims raised the temperature in the three-sided contest to succeed Mr Hague, which pits Mr Portillo against Kenneth Clarke and Iain Duncan Smith.

Ms Platell claimed in her videos that Francis Maude, Mr Portillo's leadership campaign manager, was among those privately rubbishing Mr Hague's strategy during the election.

"I still find it slightly shocking that, you know, we're fighting so hard at the moment and to find that all they're concentrating on is how they would pull it down," she said at one point in the film.

In contrast, Mr Duncan Smith was shown as an ultra-loyal supporter of Mr Hague.

As four more MPs declared their support for Kenneth Clarke last night, Mr Portillo denied the "spiteful" claims, insisting he supported Mr Hague "politically and emotionally" during the election.

Mr Maude called Ms Platell's accusations "absolutely, fundamentally, directly, diametrically the opposite of the truth".