Hague knew Lord Ashcroft's tax status for "months"

Tories under pressure to sack party donor following Hague's admission.

The Conservatives are facing calls to sack party donor Lord Ashcroft after former leader William Hague admitted that he had "known for a few months" that the peer had been avoiding tax on his overseas income.

Hague's disclosure reveals how Ashcroft, the party's deputy chairman, kept the Tories in the dark over his tax status for almost a decade. As party leader in 2000, Hague gave assurances that Ashcroft would pay "tens of millions" more in tax as a condition of being granted a peerage.

But the billionaire later struck a deal with officials that allowed him remain a "non-dom" - only paying tax on his British income.

Hague, the shadow foreign secretary, said he was not privy to the final agreement made by Ashcroft - who was twice previously denied a peerage as a tax "exile".

"I knew the Cabinet Office would set that out and agree it with Michael Ashcroft but I would not, of course, know the details of that," he said. "I was not aware of any of the details... I don't ask people what their tax status is or what they have negotiated with the Cabinet Office," he added.

Asked when he discovered the peer's tax status, he said: "Over the last few months", but added: "Of course I was very keen to support him then in making his position public."

Last night, Hague was criticised by Lord Turnball, the former head of the civil service, for failing to ensure that Ashcroft honoured his promise to become a full UK taxpayer.

Turnball said: "We had been assured by Hague that this was the real deal. It turns out that Ashcroft is being economical with the truth and that Hague fell for it."