Andrew Caldecott, counsel for the BBC, blamed Downing Street for fuelling the row over Andrew Gilligan's claims about the "sexing up" of the Iraq weapons dossier.
He acknowledged that the corporation had made mistakes during the dispute and would learn from them.
But in a withering analysis of last-minute changes to the dossier - and the "cynical" failure by Geoff Hoon, the Defence Secretary, to correct misunderstandings about its contents - he claimed that the central thrust of Mr Gilligan's assertions were accurate.
Mr Caldecott turned his fire on Alastair Campbell, Tony Blair's director of communications, for intensifying a dispute that could have been settled through the BBC's complaints unit when he appeared before the Commons Foreign Affairs Select Committee.
"Mr Campbell used more than battlefield munitions. He went strategic. He said large parts of the BBC had an anti-war agenda and that the BBC allegations against the Government were lies," he said.
Mr Campbell then wrote a letter to a senior BBC executive demanding answers to several questions by the end of the day. It was leaked before it was even received.
Mr Caldecott said: "This stampede tactic was not a dignified way for a Government to behave. Nor was it the action of someone interested in compromise or a considered response."
He argued that the BBC had broadcast reports based on Mr Gilligan's conversation with David Kelly because the subject was of great public interest.
The corporation was not arguing that the claims were true, but that they were worth putting out because of the credibility of Mr Gilligan's source, who had knowledge of conducting inspections in Iraq and of the weapons.
Mr Caldecott pointed out that two other experienced BBC reporters, Susan Watts and Gavin Hewitt, had spoken to Dr Kelly independently and had judged his criticisms worth airing.
Mr Caldecott said: "They did not know them to be true - how could they? They therefore did not present them as true but did present them as credible."
He conceded that Mr Gilligan had been mistaken to say the Government knew the "45-minute" claim to be wrong. He also said that the journalist should have contacted Downing Street in advance of the report.
But he said: "Dr Kelly did say the dossier was sexed up by Mr Campbell, that the classic example of this transformation was the 45-minute claim, that most people in intelligence weren't happy with the 45-minute claim because it did not reflect the considered view they were putting forward."
The BBC counsel suggested that revelations during the inquiry about the transformation of the dossier bore out the corporation's reports.
He pointed to the hardening up of a warning about the ability of the Iraqis to unleash a chemical or biological attack within 45 minutes of an order to do so following a note from Mr Campbell to John Scarlett, the chairman of the Joint Intelligence Committee (JIC).
"You don't need to be a student of obscure phrases to know that a statement that Iraq may be able to launch weapons of mass destruction within 45 minutes is very different from a statement that they are able to do so," he said.
Mr Caldecott said Jonathan Powell, Downing Street's chief of staff, pressed for changes which were not "cosmetic" but were of substance, at 3.45pm on 19 September, after time had run out for JIC comments.
He added that there was a general assumption that the 45-minute claim applied to strategic missiles and bombs, rather than battlefield material, but that the misunderstanding was not corrected. He said: "The reaction of Mr Hoon and Mr Scarlett bordered on cynical indifference. It is hard to put it down to anything other than political expedience."
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