Tony Blair was accused yesterday of misleading Parliament and dereliction of duty over the Government's claim that Saddam Hussein could deploy weapons of mass destruction within 45 minutes.
Michael Howard, the Tory leader, called on him to resign for going to war without asking crucial questions about Iraq's weapons. Mr Blair was under pressure to clarify why he did not know until after the war ended that the intelligence underpinning the claim related simply to battlefield munitions rather than long-range weapons capable of hitting British bases in Cyprus.
Downing Street said yesterday that Mr Blair did not find out until last summer - when the war was over.
The "45-minute warning" was included in the Government's dossier on Iraqi weapons published in September 2002. It prompted newspaper headlines that British bases in Cyprus could be attacked by Saddam. Although the Government argues that the claim was never a central part of its case for war, it lay at the heart of the allegation by the former BBC journalist Andrew Gilligan that Downing Street "sexed up" the dossier.
Mr Blair's embarrassment was compounded when it emerged that Mr Cook, who was Leader of the Commons at the time, and the Defence Secretary, Geoff Hoon, both knew that the intelligence related only to short-range weapons.
Mr Cook told the Commons yesterday that Mr Blair should make a public statement to clarify the position. He said: "I knew Iraq had only battlefield weapons because I asked the chairman of the Joint Intelligence Committee [John Scarlett] ... Is it not hard to credit that at no point between the September dossier and the March debate he did not explain to the Prime Minister the crucial distinction between battlefield weapons and medium-range weapons?" It was "equally difficult to believe that the Prime Minister's security adviser, Sir David Manning, never thought to ask".
In his diaries, Mr Cook recalled a conversation with the Prime Minister two weeks before the war which suggests Mr Blair knew the 45-minute warning did relate to battlefield chemical weapons. According to Mr Cook, Mr Blair cast doubt on whether Saddam could deploy WMD so quickly, saying that "all the effort he has to put into concealment makes it difficult for him to assemble them quickly for use".
No 10 rejected Mr Cook's version of events, insisting last night that the conversation related to the need to protect British troops against the threat that WMD might be used against them.
Mr Blair's aides dismissed the latest controversy as a storm in a teacup, saying that the time in which Saddam could deploy WMD made no difference to the danger posed by his long and short-range missiles, both of which were in breach of United Nations resolutions. Aides said the Prime Minister had merely given "a straight answer to a straight question" in the Commons on Wednesday. But the Tories scented blood. Mr Howard said: "The Prime Minister took us to war without bothering to ask a simple and obvious question. That question is whether the chemical and biological weapons he thought Iraq had could be used only on the battlefield, or put on the end of a missile to be fired at British troops in Cyprus.
"I cannot imagine a more serious dereliction of duty by a Prime Minister than failing to ask that basic question. It was the Prime Minister's duty to know every fact before he asked the public for their support. And it was also the duty of every cabinet minister to ask for those facts too - just as Robin Cook clearly did. This is a most grave state of affairs.
"If I were Prime Minister and had failed to ask this basic question, I would seriously be considering my position."
Charles Kennedy, the Liberal Democrat leader, dismissed the Tory demands for Mr Blair's head but said: "The Prime Minister's claims that he did not know what kind of weapons of mass destruction were supposed to be present in Iraq is almost incredible.
"As he made the decision to commit British troops to war, it is hard to believe that the Prime Minister didn't ask the vital questions about the nature of the threat and the weapons that they would be facing. If he did not, then his judgement must be called into question."
Tam Dalyell, the father of the House, said: "I fear the awful truth is that Blair did jolly well know on March 18 [when MPs approved the war] that any WMD were battlefield weapons - and suppressed this information from the House of Commons before the crucial vote. Had it not been suppressed, more Labour MPs would have joined us in voting against the war and maybe enough to stop military action."
Mr Blair's official spokesman accused the media of "rewriting history" and insisted that the 45-minute warning did not affect the dossier's claim that Saddam had long-range missiles capable of carrying chemical and biological warheads. "The Government's belief, the Prime Minister's belief, was that Saddam had a WMD capability and that that capability was both battlefield and long-range," he said. "The long-range issue doesn't rest on the 45-minute point."
Margaret Beckett, the Environment Secretary, dismissed Mr Howard's attack as "nit-picking of the highest order". She told BBC Radio 4: "To use it to say 'Oh the Prime Minister should resign' - do you suppose Winston Churchill went round asking precisely the kind of munition they had in the Second World War and would that have been a valuable use of his time?"Reuse content