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.
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 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 Bush.
- Independent