Dr Hussain al-Shahristani, 62, a Shia Muslim nuclear scientist tipped to become the new Iraqi prime minister, is widely respected and regarded by many Iraqis as the best man for the job at the moment.

While imprisoned and tortured at Abu Ghraib prison for 11 years under Saddam Hussein for "religious activities" he refused to help build a nuclear weapon for the country.

He had a dramatic escape from the notorious jail when it was bombed in the first Gulf War and fled to Iran with Bernice, his Canadian wife.

A devout Muslim from a prominent family, he has little political experience, but has close ties to Grand Ayatollah Ali Sistani, Iraq's most powerful Shia Muslim cleric whose support is essential for the viability of an interim government.

"He seems to be a rare thing: a non-aligned, respected exile who has forged close ties with Sistani," said Dr Toby Dodge of the International Institute for Strategic Studies.

"He is exactly what (UN Iraq envoy Lakhdar) Brahimi was looking for: a not too religious, not too political, not too secular, not too pro-American Shia who Sistani would talk to."

He added: "If you're not a party guy and you've accepted that job, it shows you're prepared to put your life on the line for your country."

It was an opinion piece in the Wall Street Journal at the end of April that is said to have convinced Mr Brahimi to contact Dr Shahristani.

Dr Imad Khadduri, an Iraqi former nuclear scientist who worked with Dr al-Shahristani in the 1970s, remembered him as "a very amiable person, witty and respectful and you'd find it hard to dislike him."

Dr al-Shahristani was not keen to be prime minister, but would serve his people if pushed, Dr Khadduri said. "It's a very noble stand." Interviewed by the Washington Post, Dr al-Shahristani said that he would accept the post reluctantly if it was offered him.

Dr Khadduri added: "But he is in a very poor position because the Americans are still foggy about their role. They will undermine him as they have many others."

His main doubt was whether Dr Shahristani had the mettle for the job, despite resisting torture, solitary confinement and the threat of execution.

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