Ministers were ordered yesterday to make public a secret document about Iraq’s weapons of mass destruction that could shed light on the origins of the Government’s claim that Saddam Hussein needed just 45 minutes to launch non-conventional warheads at British troops.

The unpublished draft document was drawn up by John Williams, who in 2002, before the invasion of Iraq, was the head of information at the Foreign and Commonwealth Office and one of the senior government spin-doctors.

Yesterday the Information Tribunal ruled that the Williams report should be made public so that people could make their own judgment as to whether its contents could have influenced the official dossier on Iraq’s weapons of mass destruction (WMDs), including the 45-minute claim.

Although the Government, under Tony Blair, acknowledged that Mr Williams had written a draft report on Iraq’s WMDs, officials said that he had done so on his own initiative, and that it was dismissed.

The Government insisted that the official dossier on Iraq’s WMDs published in September 2002 was drawn up by the Joint Intelligence Committee, then headed by Sir John Scarlett, who is now the head of MI6, and that it was based on intelligence material.

Critics of the Iraq dossier, however, accused the Government of using Downing Street and Foreign Office spin-doctors to dramatise the contents to make the case for invading Iraq.

This has always been denied. But opponents of the war will want to see whether the 45-minute claim was included in the Williams draft.

The unprecedented ruling followed a request by the New Statesman under the Freedom of Information Act for the Williams dossier to be made public.

Richard Thomas, the Information Commissioner, ruled in favour of the magazine in May last year, but the Foreign Office appealed to the tribunal.

Last night the Foreign Office said that the tribunal ruling was being studied closely.

Sources at the Foreign Office said that a minister had to give authorisation for the release of the document, and would still be in a position to claim that publication would not be in the national interest.

Lawyers for the Foreign Office told the tribunal that disclosure of the contents written by Mr Williams, who no longer works for the Foreign Office, would compromise the confidentiality of advice given to ministers — known in Whitehall as “the chilling effect”.

However, the tribunal concluded that the chilling effect would have been quite limited because of the huge amount of material about Iraq’s WMDs that had been put into the public domain by Lord Hutton. He was the former judge who chaired the inquiry into the circumstances leading to the suicide of David Kelly, the Ministry of Defence Iraq weapons expert.

Lord Hutton did not believe that the Williams draft formed a part of the process that led to the dossier on Iraq’s WMDs.

However, the tribunal raised questions about the Hutton inquiry and concluded: “We do not accept that we should, in effect, treat the Hutton report as the final word on the subject.

“Information has been placed before us which was not before Lord Hutton which may lead to questions as to whether the Williams draft in fact played a greater part in influencing the drafting of the \ dossier than has previously been supposed,” the tribunal said.

“We make no comment on whether it did so in fact. But we believe that the existence of those possible questions is a relevant factor in evaluating the public interest in disclosure.”

John Baron, the Conservative MP for Billericay, told the New Statesman: “This decision lifts the lid on government efforts to cover up the role played by spin-doctors in producing the Iraq dossier.”

The Foreign Office lawyers argued that, as the Hutton report was issued at the end of a detailed investigation into the drafting process, the public interest had been served.

The tribunal added: “We were also also invited to conclude that the disclosure of an early draft, developed by someone who was not an intelligence specialist and who was operating on his own initiative, might in fact mislead the public into believing that it represented government views which counsel for the [Foreign Office] said it did not.”

In his evidence to the Hutton inquiry, Alastair Campbell, Mr Blair’s director of communications, said that all papers and drafts on Iraq in existence before September 9, 2002, became “redundant”, and from that date, Sir John would “take all of this information, all of this material, and turn it into a new dossier”.

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