The BBC will produce a tape-recording at the Hutton inquiry in which David Kelly is said to link Alastair Campbell to last September's Iraq weapons dossier, sources at the corporation say.
The naming of Mr Campbell on the tape, believed to have been made by the Newsnight correspondent Susan Watts, is seen as significant because it is likely to back Andrew Gilligan's story of Downing Street's interference in the dossier.
Mr Gilligan also received public backing yesterday in a robust defence by the Today presenter, John Humphrys, one of the most senior journalists at the corporation, who predicted the BBC would be cleared of wrongdoing by Lord Hutton.
Mr Humphrys said: "In the long-term, I think the BBC has behaved properly. I think Andrew Gilligan did a thorough journalistic job. He has raised hugely important questions that had to be raised. He has behaved like a responsible reporter and the BBC has behaved responsibly editorially.
"So, in the long run, I don't believe it will damage the BBC at all. On the contrary, I believe if somebody like Dr Kelly had come to the BBC and talked to reporters - not just Andrew Gilligan, of course, but others as well - and said what he had to say, a man with Dr Kelly's authority and experience and seniority behind him, and we had not taken him seriously, then I think we would have been falling down in our duty."
Mr Gilligan stated on Radio 4's Today programme, and in an article in The Mail on Sunday, that Mr Campbell, the Prime Minister's communications chief, had intervened to make the document "sexier" by inserting a claim that Saddam Hussein was able to launch chemical and biological attacks within 45 minutes. Mr Gilligan's informant, it has since transpired, was Dr Kelly.
Ms Watts, Newsnight's science editor, and Gavin Hewitt, on the 10 O'Clock News, also subsequently reported about government "spin" and the September dossier, but did not mention the alleged role of Mr Campbell.
Ms Watt's tape has been referred to as the BBC's "smoking gun" in the judicial inquiry.
Downing Street sources said the tapes would back the Government's case rather than Mr Gilligan's. But a BBC source said yesterday: "The 'C word' - the name of Campbell being used by Dr Kelly - will strengthen Gilligan's position. We cannot go into details about exactly what was said, but it is helpful for the BBC."
Dr Kelly told Ms Watts the Government was obsessed with finding intelligence on an immediate Iraqi threat. The Government's insistence the threat was imminent was a Downing Street interpretation of intelligence conclusions. During this conversation Dr Kelly named Mr Campbell, it is claimed.
Giving evidence to the Foreign Affairs Select Committee last month, Mr Campbell declared: "I know who is right and who is wrong. The BBC are wrong. If that is BBC journalism, then God help us."
Thames Valley Police have released the body of Dr Kelly to his family after receiving results of toxicology tests. The results will not to be made public until a full inquest later this year.
¿ ITN and Sky will challenge the decision not to allow television cameras into the inquiry into Dr Kelly's death.