The Iraq Inquiry has delayed its report by at least six months as it argues with the Government over the release of top-secret documents.
Sir John Chilcot and his panel, who began hearings two years ago, had been expected to publish their initial conclusions by the end of the year. But in a statement yesterday, the inquiry team said its report would not be published until next summer at the earliest.
And it made clear that Sir John was still being frustrated in his attempts to obtain classified Whitehall documents that could shed light on the build-up to the war.
Sir John has repeatedly protested about the lack of co-operation from Whitehall over the release of paperwork, such as communications between Tony Blair and President George Bush before the 2003 invasion.
The statement said: "Pulling together and analysing the evidence and identifying the lessons, for a report that covers so wide and complex a range of issues and a time period of some nine years, is a significant task.
"The Inquiry has advised the Government it will need until at least summer 2012 to produce a draft report which will do justice to the issues involved."
It added that the Inquiry would need to negotiate the declassification of a significant volume of classified material with the Government to enable this to be quoted in, or published alongside, the report.
"That process has begun, but there will be a series of further major requests. The Inquiry has made clear it will need co-operation from the Government in completing this in a satisfactory and timely manner."
The statement hinted at a possible further reason for the delay, explaining that anyone the Inquiry censures would have the right to set out their own version of events one last time.
This is likely to apply to Tony Blair, who is expected to be castigated for his claims about Saddam Hussein's weapons of mass destruction, for his "sofa government" style and for failing to disclose his secret discussions with Mr Bush.