The book, "Bill and Hillary: The Marriage", has sparked uproar, and could not come at a worse time for Hillary Clinton as she attempts to forge her own political career in a bid for Congress.

The author, Christopher Andersen, claims that in 1977 she embarked on an intensely passionate affair with Vince Foster, who committed suicide in 1995.

The alleged affair took place when the two were lawyers in Little Rock, Arkensas, while Mr Clinton was governor.

Rumours of an affair first surfaced in the press soon after Mr Foster shot himself in a park outside Washington. The book does not say when the relationship ended.

'Intense romantic relationship'

Mrs Clinton's office refused to comment on the book, in which Arkansas state troopers who guarded the Clinton's mansion, reportedly said that Mr Foster used to turn up "like clockwork", often staying the night, when Bill Clinton was out of town.

Hillary told Talk that her husband had been emotionally abused as a child

Speaking on CNN's Larry King Live show on Tuesday night, Mr Andersen said: "There's no doubt in my mind that there was an intense romantic relationship between Hillary and Vince Foster."

Among the book's series of claims are that in 1982 Hillary hired an FBI agent to investigate her husband's extramarital activities, only to discover that he was seeing eight women.

It also says that when she was told the true nature of her husband's relationship with White House intern Monica Lewinsky, she slapped the president so hard it left a red mark "clearly visible to sercret service agents when he left the room".

The book's publication also coincided with Hillary own revelations about her husband's infidelities following the Lewinksy scandal.

She told the newly launched Talk magazine that the president's affairs were a result of an abused childhood, apparently in the hope of pre-empting speculation about the marriage.