Wilson first defied Saddam Hussein, then George W Bush

As acting ambassador to Iraq in the run-up to the first Gulf War, he was the last US diplomat to meet with Saddam Hussein, in 1991.

He very publicly defied the Iraqi strongman by giving refuge to more than 100 US citizens at the embassy and in the homes of US diplomats - at a time when Saddam Hussein was threatening to execute anyone who harboured foreigners.

He then addressed journalists wearing a hangman's noose instead of a necktie.

He later told the Washington Post newspaper that the message to Saddam Hussein was: "If you want to execute me, I'll bring my own [expletive] rope."

Africa mission

He returned to the headlines 12 years later, when he revealed in 2003 that he was the envoy sent to Africa to investigate reports that the Iraqi president had tried to buy nuclear material there.

I have little choice but to conclude that some of the intelligence related to Iraq's nuclear weapons programme was twisted

Joseph Wilson

In July 2003, Mr Wilson announced that his trip had disproved the allegations Mr Bush later repeated.

"I have little choice but to conclude that some of the intelligence related to Iraq's nuclear weapons programme was twisted to exaggerate the Iraqi threat," he wrote in the New York Times.

A week later, syndicated columnist Robert Novak reported that part of the reason Mr Wilson - a known critic of the Bush administration who is close to the Democrats - had been given the Niger mission was that his wife - a CIA agent - recommended him.

Little notice was taken of the revelation that Valerie Plame Wilson was a CIA agent until September 2003, when it emerged that the CIA had asked for an investigation into who leaked the information.

It is a crime to reveal the name of an active CIA operative.

Critics of the Bush administration say that the White House leaked Mrs Wilson's name in revenge for her husband's behaviour.

Mr Wilson, who turns 56 on 6 November, was a career diplomat from 1976 until 1998, specialising in Africa.

He is now a business consultant. He and Mrs Wilson, his third wife, have three-year-old twins.

He is said to have backed Al Gore in 2000 and was an unabashed supporter and donor to the Kerry/Edwards campaign for the presidency in 2004.