New doubt over uranium claim

Professor Norman Dombey, an expert on nuclear proliferation, revealed that Saddam already had enough uranium to build 142 nuclear bombs - but had no means of processing it into weapons grade material.

The latest challenge came as Mr Blair flew for talks with President Bush amid a growing crisis on both sides of the Atlantic over allegations that intelligence was exaggerated to whip up support for the war.

Mr Blair is anxious to patch up a series of post-war tensions - including a row over the treatment of Britons facing military trials at Guantanamo Bay.

But the most serious rift was caused by bitter recriminations about Britain's claim in last September's dossier on Saddam's weapons that Iraq recently tried to buy " significant quantities" of uranium from Niger.

Professor Dombey, who is an adviser to Lib-Dem leader Charles Kennedy and professor of Theoretical Physics at University of Sussex, questioned the validity of the dossier in an exclusive article in today's Evening Standard.

He said Saddam was known by both Britain and the US to be sitting on a stockpile of 500 tonnes of uranium ore - so had no need to purchase any more.

"Why on earth should Iraq need to buy more uranium from Niger as the Downing Street dossier claimed?" he asked. "Iraq had far more uranium than it needed for any conceivable nuclear weapon programme."

The fact that Saddam already owned huge quantities of the same material was well known, he said, including to the international atomic inspection agency, the IAEA.

He added: "Without enrichment facilities, this material is useless for nuclear weapons."

He said the dossier claims had looked "fishy" from the start to experts.

Although Mr Blair told Parliament that if Saddam bought fissile material, he could possess a nuclear bomb within two years, Professor Dombey said the same was true of any country - and even some universities. "Imperial College could probably build a bomb in two months if they were given enough U235," he added.

"It is also very possible that this African story is an intelligence sting."

The British uranium claim has provoked the worst row between UK and US intelligence for years. President Bush was forced to disown the dossier claim after failing to find any supporting evidence and the CIA has since dismissed it and blamed MI6 for getting it wrong.