Several papers attacked the government, accusing it of turning microbiologist Dr David Kelly, a weapons expert who worked as a UN inspector in Iraq, into a "fall guy".

The defence ministry is to launch an independent judicial inquiry if it is officially confirmed later Saturday that Kelly, who disappeared on Thursday, is dead.

That would bring a tragic twist to a convoluted tale of whether the government misled the country over its reasons for going to war against Saddam Hussein in March.

Downing Street vigorously denies this claim. Kelly was grilled by a parliamentary committee investigating the affair, and was said to be have been under considerable stress.

"Death of the dossier fall guy" was the page-one headline of the right-wing Daily Telegraph, which said that Blair had been plunged into the biggest crisis of his premiership.

In an editorial it called on Alastair Campbell, the government's director of communications and a key aide to Blair, to quit, Defence Secretary Geoff Hoon to be "held to account", while Blair needed to make "some public declaration, backed up with deeds, to show that the era of spin is over."

In a report in May, the BBC claimed Campbell had ordered a claim that Iraq could deploy chemical or biological weapons in as little as 45 minutes, be inserted into its official dossier, despite the reservations of intelligence chiefs.

Campbell launched a furious counter-offensive, with Kelly finding himself at the centre of the controversy.

The right-wing Daily Mail attacked the government over the way it had treated Kelly. On its front page it ran pictures of Blair, Campbell and Hoon, under a headline: "Proud of yourselves?"

The left-wing Daily Mirror tabloid said in an editorial that Kelly had been "hounded to death by the government", adding: "Powerful men lined up to scapegoat Dr Kelly as part of their no-holds-barred campaign to clear the government of charges of faking dossiers before the Iraq war."

A headline in the Daily Express read simply: "Thrown to the wolves."

The left-wing Guardian estimated that the political fallout from the death of Kelly "may well prove incalculable."

The Financial Times business daily said: "The death of David Kelly is an immense blow to Tony Blair's government as a whole, but if the idea forms that he was in effect 'killed by spin', it will turn into a crisis" with Campbell and Hoon in the firing line.

The Independent said in a front-page report: "Whatever the truth, there can be little doubt that the pressure of events combined to a level intolerable for Dr Kelly -- and that a good man and faithful public servant died as yet more collateral damage of this questionable (Iraq) war and the spin used to distract public attention from the real issues of whether war was justified."