The US and UK's case for going to war in Iraq suffered a blow as experts confirmed they had failed to find any evidence that Saddam Hussein had weapons of mass destruction.

A leak from the Central Intelligence Agency-led Iraq Survey Group, sent in to find the arsenal of chemical and biological weapons that President George W Bush and Prime Minister Tony Blair claimed Saddam had in his possession, says not even 'minute amounts' of any such weapons have been found.

The ISG's findings came only hours after Prime Minister Atal Bihari Vajpayee told Bush in New York that India could not send peace keeping troops to Baghdad

See: No troops for Iraq: Vajpayee tells Bush

The revelation that the coalition's weapon hunters had failed to unearth any evidence of the arms that the US and Britain said were an immediate threat to the world security is a severe blow to Blair's credibility and increases the pressure on him over the decision to go to war in Iraq.

Earlier this summer, Blair had hinted that the ISG's report would vindicate him.

The ISG leak on Wednesday night could hardly have come at a worse time for the UK prime minister. The Hutton inquiry into the apparent suicide of weapons expert David Kelly, who had serious doubts about Iraq's weapons programme, concludes on Thursday after weeks of evidence that have damaged and embarrassed Blair.

On Thursday opposition Liberal Democrat leader Charles Kennedy will tell delegates at his party's annual conference: "This is supposed to be a parliamentary democracy, but what we have seen is a small clique driving us into a war, disregarding widespread public doubts.

"If the House of Commons had known then what it knows now about the events leading up to that fateful parliamentary debate and vote on committing our forces to war in Iraq, the outcome could and should have been fundamentally different."

The leak from the ISG's interim report, due to be published next month, says US and British inspectors had failed to unearth any evidence of WMD and that it is highly unlikely weapons were smuggled out of Iraq to Syria.

No laboratories for producing chemical or biological weapons have been found and the only discoveries have been papers and computer programmes suggesting that Iraq was attempting to develop a WMD programme.

But what has emerged from the ISG's investigation is a huge deception programme by Saddam to convince the world he had something to hide, perhaps to discourage enemies. The bluff involved building fake weapons plants and stonewalling United Nations weapons inspectors.

The ISG, led by former UN inspector and CIA advisor Dr David Kay, includes intelligence officials and scientists.

In London a Downing Street spokesman said: "People should wait. The reports today are speculation about an unfinished draft of an interim report that has not been presented yet. And when it comes it will be an interim report, the ISG's work will go on.

"The UK has played a significant role in the work of the ISG, including providing its deputy director, and our clear expectation is that this interim report will not reach firm conclusions about Iraq's possession of WMD."

In Washington, CIA spokesman Bill Harlow has been quoted as saying: "Dr Kay is still receiving information from the field. It will be just the first progress report and we expect that it will reach no firm conclusions, nor will it rule anything in or out."

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