Lord Hutton said he deplored the leaking of his report on the death of weapons expert Dr David Kelly ahead of its publication.
The Sun says the report came from someone 'with no vested interest'
He said he was now considering taking legal action against the newspaper and its source.
Details of his findings were published in the Sun ahead of the report's publication at the High Court.
The Tories have blamed the government for the leak but Downing Street has denied it was responsible, as has the BBC and Alastair Campbell.
The Sun had predicted Tony Blair would be cleared of any "dishonourable conduct" but that the BBC would be accused of a series of failings.
The prime minister's official spokesman said Mr Blair was "very angry" about the leak.
Lord Hutton said advance copies of the report had been given to the those involved a day before its publication in the "interests of fairness".
Copies were given to the government, the BBC and the family of Dr Kelly on Tuesday afternoon after they agreed not to reveal its contents ahead of its publication.
Lord Hutton said: "I wish to state that I deplore the reporting of some of the conclusions of my report by a newspaper this morning."
The law lord said it was all the more regrettable given the public had only to wait half a day before the report's publication.
He said: "I am now giving urgent consideration to what investigative and legal action I should take in respect of the newspaper and its source."
The judge said efforts had been made during the inquiry to make evidence available to the public as soon as possible.
Earlier Former Downing Street spin doctor Mr Campbell said any suggestion he was to blame was "totally untrue and deeply offensive".
Tory party leader Michael Howard called for a police inquiry into the "disgraceful" leak.
Mr Blair's spokesman agreed there should be a leak inquiry involving all parties, but this was a matter for Lord Hutton.
The weapons expert apparently killed himself last July after being named as the source for BBC reporter Andrew Gilligan's story the government exaggerated its 2002 dossier on Iraqi weapons.
The paper's political editor Trevor Kavanagh said he had not seen the report, but had been given details from it by an "impartial" source over the telephone.
He would not reveal details about the source.
"What I can tell you is the source had nothing to gain financially or politically, no axe to grind, no vested interest," he told BBC Radio 4's Today programme.
He said had the report criticised Mr Blair the story would have been given just as much prominence in the paper.
The Sun reported key extracts from the report.
It said Lord Hutton would criticise BBC governors for failing to make a detailed investigation into whether Mr Gilligan's story for Radio 4's Today Programme was supported by his notes.
The paper also said the report would find there was no "dishonourable, underhand or duplicitous strategy" by Mr Blair or the government to leak Dr Kelly's name as the BBC's suspected source - the exact phrase later used by Lord Hutton.
And it said the Ministry of Defence would be criticised for not telling Dr Kelly his name could be confirmed to journalists or that it had emerged.