The long-awaited report into the Iraq War does not “shy away” from criticising leading figures involved in the conflict, Sir John Chilcot has said.
The 12-volume analysis will be released today, seven years after first being commissioned by then prime minister Gordon Brown in 2009.
Sir John, former permanent secretary at the Northern Ireland Office, has assessed the build-up, handling and aftermath of the controversial 2003 conflict, with his team's verdict set to be unveiled at 11am.
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Speaking ahead its publication, Sir John said he hoped the report would help the families of the 179 Britons who died in Iraq between 2003-2009.
"The main expectation that I have is that it will not be possible in future to engage in a military or indeed a diplomatic endeavour on such a scale and of such gravity without really careful challenge, analysis and assessment and collective political judgement being applied to it," he told the BBC. "There are many lessons in the report but that probably is the central one for the future."
The report would, he said, offer a “reliable account” of the events leading up to the 2003 invasion.
Attention is likely to focus on the assessment given to key figures in government at the time, including former prime minister Tony Blair.
The report will include details of declassified Cabinet papers, intelligence assessments of Iraq’s weapons capability and private correspondence between Blair and the former US President George W Bush.
On singling out individuals’ role in the Iraq War, Sir John said: "We didn't set out to criticise individuals from the outset. We are not a court or a judge and jury.
"On the other hand I made very clear from the start when I launched the inquiry that if we came across things which deserved criticism, of individuals or institutions, we would not shy away from making them – and indeed we have."
Relatives of British troops killed in Iraq are being given access to the report prior to its official release after 11am.
Sir John told the BBC the families had been at the forefront of the inquiry’s mind and had been "invaluable in helping to shape the report and where it would lead".
"I have been very conscious from the start that the families have high expectations and wishes to know the truth of all that happened, in particular where their relatives were affected,” he said.
"I hope they will feel when they see the report that the broad questions they have in mind will have been, if not resolved, answered to the best of our ability.
"But the key point I would like to make is by revealing all the base of evidence we have, they can see our conclusions and why we have reached them but they can make up their own minds on the basis of the evidence."
The report is expected to be 2.6 million words long. Its publication has been met with countless delays since the inquiry first began more than seven years ago.
CSW will have be providing full analysis of what the Chilcot report means for the civil service later today.