The 72-year-old Swede was on holiday in Antarctica when UN Secretary General Kofi Annan telephoned to offer him a job at the helm of the UN Monitoring, Verification and Inspection Commission (Unmovic) in January 2000.

We are not coming to Iraq to harass or to insult or humiliate them

Hans Blix

Dr Blix was a compromise choice. The UN Security Council had rejected Rolf Ekeus, the candidate put forward by the United States and Britain.

Now the Swedish diplomat's verdict on Iraqi cooperation and weapons could make the difference between war and peace.

Butler's legacy

Dr Blix's predecessor, Australian Richard Butler, was a very different sort of man.

He has been described as charismatic, but sometimes abrasive.

When he was accused of spying for the US and Israel, the Arab world denounced him.

Butler: 'Charismatic, but abrasive'

By contrast, Dr Blix keeps a low profile and has been accused of being overly concerned with Iraqi sensibilities.

Critics point to the "cultural sensitivity" training members of his organisation undergo. They see it as a sign that Mr Blix and his staff worry too much about hurting Iraqi feelings, and are therefore liable to be duped.

But the Unmovic leader says the training programme is designed simply to prevent members of his team from appearing obnoxious - a label that clung to previous weapons inspectors.

"We are not coming to Iraq to harass or to insult or humiliate them," he told the BBC's Breakfast with Frost. "That's not our purpose."

Iraqi history

Mr Blix has a law PhD, and has pursued his studies in Sweden, England and the US.

He joined Sweden's foreign ministry in 1963, and became its head 15 years later.

He has written several books concerning international and constitutional law. In 1980, he campaigned to retain Sweden's nuclear energy programme.

Not seeing something, not seeing an indication of something, does not lead automatically to the conclusion that there is nothing

Hans Blix

In 1981, Dr Blix became director general of the International Atomic Energy Agency - a post he retained until 1997.

The job called for him to oversee, among other things, inspections of Iraq's nuclear programme.

During that time, Saddam Hussein's regime managed to hide an advanced nuclear weapons development programme from the IAEA. But Mr Blix said the experience taught him something.

"It's correct to say that the IAEA was fooled by the Iraqis," he told the Guardian newspaper.

"But the lesson was learned. Because not seeing something, not seeing an indication of something, does not lead automatically to the conclusion that there is nothing."