Alastair Campbell fiercely denied forcing the insertion of the controversial "45-minute" claim into the September dossier that set out the Government's case for war in Iraq.
The Downing Street director of communications told the Hutton inquiry that all elements of the dossier were in the "ownership" of John Scarlett, chairman of the Joint Intelligence Committee (JIC), who had rebuffed offers by Downing Street and the Foreign Office to help with its drafting.
Asked if he had any influence on the inclusion of the 45-minute claim, as reported by the BBC's Andrew Gilligan, Mr Campbell said it had been present in drafts of the dossier dating from 10 September. "I had no input, or output, or influence on them at any stage of the process," he said.
Mr Campbell said the operation by the intelligence agencies to produce the dossier was unprecedented, adding: "That was a further reason I was so meticulous about the way I behaved in relation to ... the preparation of the dossier."
Mr Campbell said Tony Blair had decided during his summer break in August last year that the time had come to produce a document setting out as much intelligence information as possible on Iraq's suspected weapons arsenal.
An earlier document, begun in spring 2002 and pulling together information about Iraq and three other countries, had been abandoned because it "was not terribly good", but work began on 5 September on a fresh version concentrating entirely on Iraq. Mr Campbell insisted that all papers circulating in Whitehall at that point about the Iraqi threat were "redundant".
Reading from his diary, he said he had told a meeting on that day that the planned dossier had to be "revelatory", new and part of a bigger case underlining the threat from Saddam Hussein. John Williams, the press secretary at the Foreign Office and a former journalist, offered his services full-time to write it.
Explaining why the offer was refused, Mr Campbell said: "The decision was taken at that meeting, or certainly by 9 September, that John Scarlett felt he had to have ownership of the dossier."
Mr Campbell said he had emphasised that its credibility depended "fundamentally" on its being the work of the Joint Intelligence Committee.
Mr Campbell told the inquiry that four days later, at a meeting with Mr Scarlett, he urged that the dossier's style be toned down. "I said: 'The drier the better - cut the rhetoric ...' I think there were areas where the language was too colourful. I also said the more intelligence-based it was the better."
He told of a meeting on 9 September with three senior officers from the Secret Intelligence Services angry at press reports that they were worried about the way in which the dossier was being compiled. "These stories did not remotely reflect their views," he said.
Asked by Lord Hutton whether there was any indication of disquiet in the "lower ranks" of the services about the dossier, Mr Campbell replied: "Not at that stage."
James Dingemans, counsel for the inquiry, asked whether he became aware of such worries at a later point. Mr Campbell responded: "Only through what I read in the newspapers, which was causing us ... some concern."
Lord Hutton asked if he knew the origin of the 45-minute claims, which first appeared in a draft version of the dossier on 10-11 September. Mr Campbell said: "I knew it had come from the JIC but I wasn't aware either of the raw information it was based on or the sourcing."
He was shown a number of Downing Street e-mails on the production of the dossier. One, from the special adviser Philip Bassett, said: "Very long way to go. I think we are in a lot of trouble with this as it stands now." Godric Smith, the Prime Minister's official spokesman, said: "It's a bit of a muddle and needs more clarity."
Mr Campbell said: "If I took any of [thee-mails] on board, it would have been this one." But he stressed he saw only a small proportion of e-mails sent to him.
Mr Dingemans turned to the foreword to the dossier in which the Prime Minister eventually warned of the "serious and current" threat from Saddam's WMD. Mr Campbell said he had produced a draft version, shown to Mr Blair and senior officials who added their comments, and it was finally approved by Mr Scarlett.
The press chief was shown the 17 September e-mail from Jonathan Powell, Mr Blair's chief of staff, raising his concerns that Saddam was not an imminent threat. He said: "I think what Jonathan is doing there is making an observation that is consistent with what John Scarlett had been doing."
Mr Campbell denied there had been a rush in the week before the dossier's production.
Mr Dingemans asked, "Do you think people in [David Kelly's] position thought that Downing Street was over-involved in the production of the dossier?" Mr Campbell replied: "They should not have done so because this was going to be a major international event involving the Prime Minister."
In an e-mail, Mr Powell wrote: "Alastair, what will be the headline in the Standard [London Evening Standard] on the day of publication [of the dossier]?" The inquiry was then shown a copy of the Evening Standard's front page on the day of publication. The headline read: "45 minutes from attack."
Mr Dingemans asked, to laughter: "Did you have any part in the headline?" Mr Campbell answered: "I did not. I do not write headlines in the Evening Standard."