Mr Whelan, who quit his post at the Treasury after he was named and blamed as the source of a report of a secret pounds 373,000 loan from Geoffrey Robinson to Peter Mandelson, the former trade secretary, is reportedly set to make pounds 500,000 from the book.
Curtis Brown, his literary agent, says he has been "showered with offers" of up to pounds 250,000. Newspapers are said to be prepared to pay pounds 200,000 for serialisation.
Mr Whelan, 44, a fanatical Tottenham Hotspur supporter, yesterday refused to confirm the amounts being offered: "If those figures are true I'll be able to buy Spurs a new player and pay off Peter Mandelson's house loan for him." Mr Whelan is now a chat-show host on BBC Radio Five Live.
He would not comment on the contents of his book, but his review of the journalist Paul Routledge's unauthorised biography of Mr Mandelson, entitled Mandy, hinted it would be explosive: "Mandy goes a fair amount of the way to revealing the inner machinations of the rise of New Labour," he wrote. "Of course, there are probably lots more details that neither Paul Routledge, nor anybody else has told - yet."Reuse content