Revenge of the con man: bitter down under, Foster hints at his 'weapon of mass destruction'

Tony Blair would no doubt sleep a little easier if the earth swallowed up Peter Foster, the Australian con man at the centre of the Cheriegate scandal. But, like a bad penny, Mr Foster keeps turning up.

The twice-convicted fraudster has returned to haunt the Prime Minister, making allegations about his personal life that have been printed in newspapers around the world. This weekend, as Mr Foster prepared to launch legal action in London that he claims will further embarrass Mr Blair, he told The Independent on Sunday that he had "irrefutable evidence" to back up the claims.

In an interview from his home on the Queensland Gold Coast, Mr Foster made clear that he is still fuming about the way he was treated by Downing Street over Cheriegate. He also claimed that Carole Caplin, his former girlfriend, exerted an unhealthy amount of influence over Mr Blair. "She gives him advice on strategies for handling Gordon Brown and dresses him down to his boxer shorts," he said.

Given Mr Foster's background, his claims have to be taken with a monumental dose of salt. But he has already demonstrated the mayhem he can cause. In December 2002, Cherie Blair was forced to go on television to make a weeping admission of naivety after it was revealed that Mr Foster had helped her to buy two cut-price flats in Bristol.

It was through Ms Caplin, Mrs Blair's close friend and "lifestyle guru", that Mr Foster met the Prime Minister's wife. While Mr Foster was forced to leave Britain following Cheriegate amid moves to deport him, Ms Caplin remained a member of the Blairs' inner circle, despite the reservations of Downing Street aides. The friendship appears to have cooled of late.

"Everyone always assumed that the strength of that relationship was based on Carole and Cherie," Mr Foster told The Independent on Sunday. "In fact, it was very definitely Tony and Carole. That's the true friendship. She has been there since day one ... The influence she wields over Tony is extraordinary. He was ringing her nearly every night, telling her everything about his day at work and the people he was seeing. He would ring her to ask what tie he should wear with what shirt. They would talk about Gordon Brown, and she told him to make sure he had another person in the room when he confronted him," he said. "At first I was in awe when he used to ring up and I answered the phone. Then after four or five months, it was like 'bugger, he's on the phone again'. The loyalty that Tony has given to Carole, in the light of totally horrific publicity, that's not politics. He protected her and stood up for her against Alastair Campbell."

Mr Foster, who has been in jail in Britain, Australia and the US, claimed that Mr Blair told Ms Caplin after returning from a visit to President Bush's ranch in Texas that war in Iraq was inevitable. "He told her they had made up their minds that war was going to happen; the only question was when. The task he had before him now was to convince the British people it was necessary, and the UN was just going to be nuisance value."

Mr Foster parted company with Ms Caplin before he left Britain and, since returning to Australia a year ago, has written a biography that "sets the record straight", he says, about the relationship between himself, Ms Caplin and the Blairs. The book, co-written with the Daily Mail's Sydney correspondent, Richard Shears, was supposed to be published last month, but is in doubt now because he has fallen out with the Mail.

Allegations about Mr Blair's personal life that Mr Foster has made to foreign newspapers do not appear in the 140,000-word biography,A Question of Deceit. But Mr Foster claims that private emails given to Mr Shears to corroborate claims made in the book prove that he is telling the truth. Those 5,000 emails are the subject of an acrimonious dispute between Mr Foster and the newspaper. The former, who claims that the Mail bought the book's serialisation rights for £500,000, says they were supposed to be returned to him by 20 February, together with photographs, diary notes and records of telephone conversations. They were not returned, and so Mr Foster went to Brisbane Supreme Court last week to seek an injunction demanding them back. In the absence of Mr Shears, who left the country last month, the judge declined to comply. An aggrieved Mr Foster maintained that his motives were purely selfless: the material was so sensitive that it could topple Mr Blair - and he did not want that on his head.

The Mail insists that the book deal was with Mr Shears and it was not party to it. What seems certain - or perhaps not so certain, depending on whom you believe - is that the deal, whatever it entailed, hit a wall when Mr Shears failed to give back the emails and other material. Hell hath no fury like a con man scorned and Mr Foster has dispatched his barrister, Sean Cousins, to London to argue his case in the High Court on Tuesday. If he does manage to have his case heard, there will be yet more headlines linking the Blairs to their Australian nemesis.

Mr Foster said the Mail had lost interest in the book - the one it claims to have nothing to do with - and was absorbed by the far more sensational corroborative material. The newspaper, he said, has engaged three computer experts to check the authenticity of the emails.

"The Mail has a hidden agenda," he claimed. "They want to bring about the downfall of the Prime Minister. They had access to my computer and 5,000 emails which are a lot juicier than the material I put in the book. If I had wanted that material in the book, I would have put it in. I would now prefer the book not to be published. I'm over it." The emails, he said, contained information highly damaging to the Blairs and would be "a weapon of mass destruction to Tony Blair's enemies". He declined to go into detail, beyond alleging that there was evidence of financial impropriety beside which Cheriegate paled.

Having bounced back into the spotlight, Mr Foster appears to be in no hurry to go away. His book, he promised, was "interesting, funny, insightful". He added: "I've got people interested in the movie rights." A soap opera might be more fitting.