The Information Commissioner ordered civil servants to release undisclosed emails and memos about a draft of the dossier which supposedly set out the threat posed by Saddam Hussein.
Richard Thomas flatly rejected Government claims that the comments - kept under wraps during a three-year legal battle - could jeopardise national security.
He said it was clearly in the public interest to know what alterations to the dossier were proposed in the days before it was published.
This was because the undisclosed material could provide 'evidence that the dossier was deliberately manipulated in order to present an exaggerated case for military action'.
Lord Hutton's inquiry into the death of government scientist Dr David Kelly heard that last-minute changes to the draft were suggested by Tony Blair's spin supremo Alastair Campbell, and subsequently adopted by intelligence chiefs.