Two ex-civil service chiefs have joined the condemnation of Britain's former Washington ambassador Sir Christopher Meyer over revelations in his memoirs.
The memoirs detail conversations in the Majors' bedroom
Lord Armstrong said the details broke personal confidences, while Lord Butler said the relationship between ministers and civil servants could be threatened.
Critics including Lord Heseltine say Sir Christopher should quit as Press Complaints Commission chairman.
He has not commented on the furore over his memoirs of the six years to 2003.
Extracts of the book, DC Confidential have been published in two newspapers.
In the extracts, Sir Christopher calls some ministers "pygmies".
He also criticises Prime Minister Tony Blair for failing to use his leverage in Washington to delay the Iraq war to allow for better planning for the post-Saddam Hussein era.
But Lord Butler told BBC Radio 4's The Week in Westminster books like Sir Christopher's "inhibited frank conversation" between ministers and officials.
"The position of a civil servant and the position of an ambassador is that you have to be the link between the politician and the Government," he said.
"For civil servants there has to be 'self-denying-ordinance' - you can't cover this by rules - I just think that it's an obligation of the profession and in the interests of the profession that you maintain these confidences."
He said he would like to see his former colleagues and others within the civil service observe these conventions, as well as the new breed of special advisers.
And he said that during the last days of the Major government, when he was Cabinet Secretary, senior Tory politicians were afraid to argue their points for fear they would end up in the media.
"That greatly inhibited frank conversation. If you can't have frank conversation in the Cabinet then things have come to a pretty poor pass."
'Breach of trust'
Lord Armstrong, his predecessor, said Sir Christopher had "breached a trust", adding that he had made it "far harder to establish that relationship of trust and confidence which is at the heart of the relationship in government between ministers and civil servants".
Meanwhile, Lord Heseltine told BBC News: "I think that Christopher Meyer should leave his position as chairman of the PCC."
Jack Straw says Sir Christopher was a marginal player on Iraq
The former deputy prime minister's sentiments were echoed by Labour MP Alan Keen, a member of the Commons culture committee. Sir Christopher was press secretary to Sir John Major when he was prime minister and the book details his early morning talks in the Majors' bedroom.
Foreign Secretary Jack Straw has said Sir Christopher was not nearly as involved in discussions about Iraq as he now tried to suggest.
Sir Christopher has not yet responded to his critics but is due to be questioned on the issue next month by the Commons public administration select committee.
A spokesman for the PCC said: "If anyone did complain about the serialisation, then Sir Christopher would not play any part in the investigation or decisions."
Bob Satchwell, director of the Society of Editors, said the row strengthened the view that Sir Christopher was independent of politicians and the media.
Meanwhile, journalist and former independent MP Martin Bell welcomed the revelations.
He told BBC Two's Newsnight that Sir Christopher "has told us things we needed to know" about the build-up to military action in Iraq because he was a "primary witness" to this process.
"He is telling us things we didn't know and we are surely benefiting from finding out," he added.