The award of a knighthood to John Scarlett was described as "utterly astonishing" by MPs yesterday.
Sir John, who oversaw the production of the so-called "dodgy dossier" which claimed that Saddam Hussein could launch a missile attack in 45 minutes, is made a Knight Commander of the Order of St George in the New Year honours.
But Angus MacNeil, SNP MP for Na h-Eileanan An Iar, said Tony Blair had shown "breathtaking arrogance" in approving the award.
"John Scarlett has been awarded an honour for services to diplomacy. Services to creative writing might have been more appropriate," he said.
Sir John's role in the production of the infamous dossier was exposed in Lord Hutton's inquiry into the death of the weapons scientist Dr David Kelly.
Lord Hutton said that he might have been "subconsciously influenced" by political pressure that caused him to strengthen the wording of the dossier.
The Conservatives, however, refused to be drawn on the knighthood for the man who is now head of the Secret Intelligence Service (MI6). David Cameron's New Year message pledges to give "wholehearted backing" to measures to "enhance our security services".