BBC Political correspondent Emma Udwin: Mr Blair arrived back in Britain last night with some major repair work to do

In a book serialised in the Sunday Times, Margaret Cook gives intimate details of the pair's troubled love life.

She accuses him of taking six lovers, including his secretary Gaynor Regan - the woman he married after his divorce.

She also claims her 52-year-old ex-husband had a habit of drinking heavily, in one incident in 1987 passing out on the floor of a hotel with a brandy bottle.

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The Tories scrambled to capitalise on the latest Labour scandal, with Shadow Foreign Secretary Michael Howard calling for Mr Cook to resign or be sacked - not over his ex-wife's book, but because of his "disastrous" term in office.

Speaking to BBC Radio 5 Live, Mr Howard blasted the foreign secretary's handling of the civil war in Sierra Leone, said he had "bungled" the royal visit to India last year and had "dithered" over the conflict in Kosovo.

"We don't need Mrs Cook's book to draw attention to the record of Robin Cook as Foreign Secretary and it is a disastrous record," he said.

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A friend speaking on Mr Cook's behalf rubbished the claim that he had a drink problem.

"It is simply not believable that he could have had a drink problem, especially in 1987, when he was running the Tories ragged and making his reputation as the best parliamentary performer of his generation.

"No one who knows Robin and who knows how hard he works is going to believe this."

A Foreign Office spokesman said Mr Cook had declined to comment about the book.

A Downing Street spokesman also refused to comment on Mrs Cook's book, saying: "We are not in the business of helping to sell books."

'Jealous of Brown'

In her book A Slight and Delicate Creature, Mrs Cook portrayed the foreign secretary as cold and unfeeling, saying he abandoned her at London's Heathrow airport on the eve of a holiday when told his affair with Ms Regan had been discovered by the press.

Mrs Cook could provoke further tensions within the Cabinet by alleging that Mr Cook is increasingly jealous of Chancellor Gordon Brown and "hates" former Trade Secretary Peter Mandelson.

Robin Cook married Gaynor three months after affair was revealed

She also claims that her ex-husband suffered "terrible guilt" over sacrificing his left-wing, anti-nuclear principles for political advancement and writes that Tony Blair "sold his soul to the devil" to get Labour elected in 1997.

But in an interview with the Sunday Times, Mrs Cook, 54, denied she was trying to wound her former husband.

"I am really not motivated by revenge of any description," she said.

"If I had wanted to bring down the world around Robin's ears I would have written it very differently."

'Sex life suffered'

Mrs Cook said her 28-year marriage gradually soured as she realised her husband was taking a string of lovers.

Their sex life suffered during his affairs - and recovered when they ended, she said.

She recounted in detail the day in August 1997 when Mr Cook told her their marriage was over at Heathrow, after Mr Blair's press secretary Alastair Campbell telephoned to tell Mr Cook a newspaper had discovered his latest affair.

The couple divorced soon afterwards. Mr Cook married Ms Regan in 1998.