The Prime Minister and his communications chief Alastair Campbell have repeatedly denied embellishing the document and insisted it was supported by the intelligence services.
But they stood accused of lying to the country last night after the intelligence men told the Hutton Inquiry that "spin merchants" in Downing Street "over-egged" evidence against Saddam Hussein for their own purposes.
The stakes could not be higher. The Prime Minister told the inquiry last week that BBC allegations of "sexing up", if true, would have "merited my resignation".
And both Mr Campbell and Foreign Secretary Jack Straw told a Commons committee earlier this year that the intelligence services had no complaints about the dossier.
The two men giving evidence to the inquiry over the death of weapons expert Dr David Kelly were retired MoD scientist Dr Brian Jones and a chemical weapons expert identified only as Mr A.
They revealed how they and their colleagues were ignored when they voiced concerns about the Iraq dossier issued in September last year. One claimed the "shutters came down" when reservations were raised.