The row over claims that the Government “spun” its way into war with Iraq is likely to be reignited after the release of the document by the Cabinet Office.
The memo, released after a long-running Freedom of Information battle, shows Mr Blair’s officials knew seven years ago that the threat from Saddam was not immediate.
Despite the warning, the Government’s dossier on Iraq’s weapons of mass destruction included a claim that Baghdad was ready to launch an attack within “45 minutes”.
Lord Hutton cleared the Government in 2004 of the charge that it tried to manipulate intelligence to pave the way for war.
But today Whitehall released a memo from former Cabinet Office defence expert Desmond Bowen, who later won promotion to policy director at the Ministry of Defence, which shows he disagreed Saddam posed an immediate threat.
The September 2002 memo, written to then Joint Intelligence Committee chairman John Scarlett and copied to Alastair Campbell, provides comments on an early draft of the government dossier on Iraq.
Mr Bowen wrote: “The question which we have to have in the back of our mind is ‘why now?’ I think we have moved away from promoting the idea that we are in imminent danger of attack and therefore intend to act in a pre-emptive self defence.”
Another email published today underlines ministers’ focus on how to get their message across in the media.
A memo from then Foreign Secretary Jack Straw’s office stresses the dossier had to be shown on the Sky News video “wall”.
The email from Mr Straw’s private secretary Mark Sedwill suggests the dossier needed a “very simple table”.
Mr Sedwill wrote: “This should be brief enough to get onto the Sky wall ie no more than 5 bullets.”
Another email, apparently from an intelligence official, says a part of the dossier on chemical and biological weapons would be “likely to give a misleading impression”.
A further email, from unnamed officials, says “there is nothing we can point to that we know for sure is going to the BW [Biological Weapons] programme”.
Mr Blair published the WMD dossier in September 2002, which critics believe paved the way for war the following spring.
An inquiry by Lord Butler found blunders in its compilation, with the “45 minutes” claim based on unreliable evidence.
A separate “dodgy dossier” was published in early 2003. It was discovered to have sections copied off the internet.