Thirty people, including Tony Blair, are set to be heavily criticised by John Chilcot's Iraq War inquiry

Thirty people, including Tony Blair, are set to be heavily criticised by the Chilcot Inquiry in its ‘devastating’ attack on the Iraq War.

Well-placed sources say that ‘approximately 30’ people have been sent letters by chairman Sir John Chilcot warning them that they will be criticised in his report into the 2003 invasion.

They include the former Prime Minister and ex-Foreign Secretary Jack Straw, as well as a host of other Labour politicians, Whitehall mandarins, diplomats and intelligence officials.

The Mail on Sunday understands that Chilcot’s million-word report on the conflict is ‘largely finished’.

Sources close to the inquiry say its strongly worded criticisms of the way the war was handled make a nonsense of claims that it will be a ‘whitewash’.

Downing Street insiders expect the report to be a ‘devastating’ indictment of the Blair Government and large sections of the Whitehall establishment.

Among the most explosive parts will be the details of 30 secret letters, notes and conversations between Blair and former US President George W. Bush in the run-up to war.

Contrary to earlier claims, full details of the way that Blair privately promised Bush that he would go to war against Saddam – without telling MPs and British voters – will be published. Blair and Bush are said to have ‘signed in blood’ their agreement to oust Saddam Hussein in secret talks at the President’s ranch in Crawford, Texas, a year before the start of the war.

Blair’s candid words in their secret letters – with redactions to protect sensitive military and intelligence issues only – will be published word for word. Only the ‘gist’ of Bush’s comments will be published to avoid embarrassing a key foreign ally.

The disclosure that up to 30 people face being criticised is a major surprise. Chilcot was asked by MPs last week to say how many people had been told they will be criticised in the report, but he refused point-blank. ‘At the risk of being obdurate, I mustn’t,’ he replied. ‘If I start to give numbers people can work out who might be involved.’

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Among the most explosive parts will be the details of 30 secret letters, notes and conversations between Tony Blair and former US President George W. Bush in the run-up to war

Equally surprising is the disclosure of the severity of the criticism meted out to those responsible for the war. A source said: ‘The suggestion that it is going to be a whitewash is quite wrong. Downing Street expects it to be devastating.

IRAQ INQUIRY BY NUMBERS 15/06/2009: Date when the inquiry was announced by the then PM Gordon Brown 150: Number of witnesses who gave public evidence 02/02/2011: The date of the last hearing 7,000: Government documents to be included in the final report 30: Notes from Tony Blair to George W. Bush examined by the inquiry £790: How much Sir John Chilcot was paid per day £9,016,500: Total cost of the inquiry as of March 2014 2,070: Days since the inquiry was announced 461,000: Estimate of number of Iraqis who died as a result of the invasion 179: UK Service personnel who died during Operation Telic, as the Iraq War was known Advertisement

‘It is also wrong to say Chilcot will only publish the gist of what Blair said. His words will be published word for word.’

‘There will be redactions where appropriate but it will be quite clear to see what he said and what he meant. Bush’s comments will be less detailed but that is necessary as it is not up to Britain to publish details of what a US President says.’ Sir John fought a dogged battle with Cabinet Secretary Gus O’Donnell and his successor Jeremy Heywood to win approval to publish the comments. O’Donnell refused to give way and it took Sir John a year to force Heywood to agree.

It has led to claims of a conflict of interest involving Heywood, who worked in No 10 for Blair.

The dispute over publishing the confidential communications between the two leaders is the main reason for the delay in publishing the findings of the inquiry, which was set up in 2009.

It meant Sir John could not fulfil until recently his duty to send so-called ‘Maxwell letters’ to those whom he intends to criticise in his report. Some of the 30 or so have received letters running into hundreds of pages. One individual is said to have received a 1,200-page letter from the inquiry.

Horrifying: A British soldier escapes from a burning tank after it was petrol-bombed in Basra, Iraq

Questioned by MPs last week on the delays, Sir John stressed the importance of publishing the Blair-Bush correspondence in full: ‘The question of when and how the PM made commitments to the US about the UK’s involvement in military action in Iraq and subsequent decisions is central to our considerations.’ They were at the heart of the inquiry, he added, because they ‘illuminated the Prime Minister’s position at critical points’.

Sir John did not conceal his satisfaction at winning his power struggle with Heywood: ‘It came to the point where it was no longer possible to sustain the doctrine that these documents could not be disclosed, but it took a long time.’

He had ‘nibbled’ away until Heywood finally crumbled.

In an acrimonious Commons debate earlier this month, Straw, who was interrogated three times at the Chilcot Inquiry, appeared to strike a defensive tone. People who faced criticism had a right to ‘be given a proper opportunity and sufficient time’ to respond, he said.

And he revealed he feared Press reports that it would be a ‘whitewash’ could pressure Chilcot into drawing ‘more stark conclusions than the evidence would allow’.