LONDON: The long-delayed Chilcot inquiry report — the official British inquiry into the Iraq war — will be published without crucial evidence that would reveal what Tony Blair promised President George Bush in the runup to the invasion, government sources have indicated.

Sir John Chilcot and his four-member panel have been at loggerheads with the Cabinet Office, the chief protector of government documents, over the disclosure of evidence they have described as of central importance in establishing the circumstances that led to war. In sharp exchanges with the former cabinet secretary Lord O’Donnell last year over the refusal to disclose details of correspondence and conversations between Blair and Bush, Chilcot said their release would serve to “illuminate Mr Blair’s position at critical points” in the runup to war.

O’Donnell consulted Blair before suppressing the documents. Chilcot, who has seen the documents, told O’Donnell last year: “The question when and how the prime minister made commitments to the US about the UK’s involvement in military action in Iraq, and subsequent decisions on the UK’s continuing involvement, is central to its considerations.”

Chilcot referred to passages in memoirs, including Blair’s autobiography, A Journey, and disclosures by Jonathan Powell, Blair’s chief of staff, and Alastair Campbell, his former head of communications.

Those publications, and the refusal to disclose Blair’s notes, Chilcot said, “leads to the position that individuals may disclose privileged information (without sanction) whilst a committee of privy counsellors established by a former prime minister to review the issues cannot”.

O’Donnell told Chilcot that releasing Blair’s notes would damage Britain’s relations with the US and would not be in the public interest. “We have attached particular importance to protecting the privacy of the channel between the prime minister and president,” he said. Sir Jeremy Heywood, O’Donnell’s successor, is believed to share O’Donnell’s approach to the release of the documents. It may be decades before the notes are released.

By arrangement with the Guardian