A former US ambassador who questioned the Bush administration's justification for war in Iraq accused vice-president Dick Cheney's office of masterminding a smear campaign against him and his wife, a CIA officer, in a book published yesterday.

Joseph Wilson's book, The Politics of Truth, is the latest volume by a former government insider to take aim at the Bush administration's conduct of the war on terror.

Mr Wilson - who served in Africa and Iraq and was the last American diplomat to meet Saddam Hussein - returned to prominence last July when he published a newspaper article accusing the White House of twisting intelligence on Iraq's pursuit of a nuclear weapons programme to bolster the case for invasion.

Soon afterwards, administration officials leaked the identity of his wife, Valerie Plame, an undercover CIA official tracking the international trade in weapons of mass destruction.

The leak represented a serious felony under US law and a federal investigation is nearing completion in Washington into who was responsible.

"It's coming to a close, and my understanding is there are going to be indictments," said one source familiar with the investigation.

If those indictments include senior administration officials, the consequences could be seriously damaging for the White House.

Mr Wilson does not definitively unmask the guilty party but he voices his suspicions, based on his own inquiries, about a group of senior right-wing officials.

In The Politics of Truth, he claims that a meeting was held in March 2003 in Mr Cheney's office "to do a workup on me".

"As I understand it, this meant they were going to take a close look at who I was and what my agenda might be," Mr Wilson writes. He concedes he does not know who chaired the meeting but claims it was "either the vice-president himself or, more likely, his chief of staff, Lewis ('Scooter') Libby".

In 2002, Mr Wilson was sent to Niger by the CIA to investigate documents purporting to prove Iraqi attempts to buy uranium.

He found the claims were groundless and the documents turned out to have been forged.

Nevertheless, the claim that Iraq was trying to buy uranium in Africa found its way into President Bush's state of the union address in January 2003, making the case for war.

In March, Mr Wilson began to make his concerns known about the claim, and that is when he says he began to be targeted by the administration.

"Over a period of several months, Libby evidently seized opportunities to rail openly against me as an 'asshole playboy' who went on a boondoggle 'arranged by his CIA wife' - and was a Democ ratic Gore supporter to boot," Mr Wilson writes.

The spokesman for the vice-president's office was said to be travelling yesterday and unavailable for comment. In the past the White House has emphasised Mr Wilson's links to the Democratic party.

Mr Wilson said that he did make a contribution to the Al Gore presidential campaign in 2000, but pointed out he also made a contribution to the George Bush campaign at the time of the 2000 Republican primaries. He has become a foreign policy adviser to the John Kerry campaign, but said that was only after the fiasco over Iraq intelligence and the White House campaign against himself and his wife.

Mr Wilson comes closest to blaming Mr Libby for his wife's unmasking. "The man attacking my integrity and reputation - and, I believe, possibly the person who exposed my wife's identity - was the same Scooter Libby..." he writes.

"He is one of a handful of senior officials in the administration with both the means and the motive to conduct the covert inquiry that allowed some in the White House to learn my wife's name and status, and then disclose that information to the press."

He also names Elliott Abrams, a senior White House adviser on the Middle East, and Karl Rove, the political mastermind behind the president's re-election strategy, as members of that group.

"According to my sources, between March 2003 and the appearance of my article in July, the workup on me that turned up the information on Valerie was shared with Karl Rove, who then circulated it in administration and neo-conservative circles," Mr Wilson claims in his book. He also accuses Mr Rove of "pushing" the story about his wife in the media after her identity was revealed.