Downing Street overruled senior Ministry of Defence officials who wanted to protect the identity of David Kelly and prevent him appearing before the Foreign Affairs Select Committee, according to Whitehall sources.
Geoff Hoon, the Secretary of State for Defence, is expected to be questioned by the judicial inquiry into Dr Kelly's death over whether he sided with Downing Street on the unmasking of the government scientist. Dr Kelly is understood to have been given guarantees from the MoD that his identity would remain secret.
The revelation calls into question Downing Street's assertion that the MoD took the lead in dealing with Dr Kelly after he admitted he had met Andrew Gilligan, the BBC journalist who claimed No 10 had "sexed up" a dossier on Iraqi weapons.
Downing Street conceded yesterday that it had been consulted by the MoD over the handling of the Kelly affair.
An important issue for Lord Hutton's inquiry will be whether Downing Street was determined to disclose Dr Kelly's identity to help it in its dispute with the BBC over Mr Gilligan's claim.
A senior Whitehall official said: "There was a lot of concern about the way things were going. There was a feeling at a very high level that we must do our utmost to protect the man.
"Some of us felt that David Kelly's identity should not be disclosed at all. However, the view from No 10 was that this was untenable; there were enough clues for the media to track him down."
The officials, including one of the highest-ranking civil servants in the MoD, believed the matter could be dealt with< internally without the weapons expert being identified. Among those involved in the MoD meetings were Mr Hoon; Sir Kevin Tebbit, the permanent secretary; Pam Teare, the director of news, and Richard Hatfield, the personnel director.
There were also regular telephone calls from Downing Street including, it is claimed, from Alastair Campbell. MoD sources confirmed that No 10 demanded, and was told, Dr Kelly's name. Asked yesterday if Mr Campbell was consulted on the release of Dr Kelly's name, Tony Blair's official spokesman said: "We were consulted, and the MoD was the lead department and remained the lead department."