Police have confirmed that the expert at the centre of the Iraq dossier row bled to death from a cut to his wrist, as Tony Blair comes under increasing pressure over the affair.
Tony Blair called for restraint
Dr David Kelly, 59, was named as the possible mole behind a BBC report that Downing Street communications director Alastair Campbell "sexed up" a dossier setting out the
case for war.
A senior officer said a knife and a packet of painkillers had been found close to where his body was discovered in woodland near his home in Oxfordshire on Friday.
Dr Kelly's family said he was a "loving, private and dignified" man, adding that recent events had made his life "intolerable".
In an e-mail reportedly sent to a New York Times journalist hours before his death, Dr Kelly had apparently warned of "many dark actors playing games".
The government will now hold an independent inquiry into the circumstances surrounding his death.
The prime minister has faced tough questions over the government's handling of the affair.
He was asked if he had Dr Kelly's death on his conscience during a press conference in Hakone, Japan - the first leg of his Far East tour.
But Mr Blair would only express his "deep sorrow" for Dr Kelly and his family and said: "I don't think it is right for anyone, ourselves or anybody else, to make a judgment until we have the facts."
He called for "respect and restraint" until the full circumstances were known.
Mr Blair also refused to be drawn when asked if defence secretary Geoff Hoon or Mr Campbell should resign.
Another reporter shouted: "Have you got blood on your hands Mr Prime Minister? Are you
going to resign over this?"
The BBC's political correspondent Guto Harri said the prime minister looked under "enormous emotional strain".
Mr Hoon said the death of Dr David Kelly was "shocking and tragic".
"It is only right that we do our utmost to establish the full circumstances surrounding this tragedy," he said.
"Accordingly, the government has invited the Right Honourable The Lord Hutton urgently to conduct an investigation into the circumstances surrounding the death of Dr Kelly.
"The government will provide Lord Hutton with the fullest co-operation and expects all other authorities and parties to do the same."
Mr Hoon also denied that the MoD had been responsible for releasing Dr Kelly's name into the public arena.
Confirming Dr Kelly's death, acting superintendent David
Purnell said: "A post-mortem has revealed that the cause of death was haemorrhaging from a wound to his left wrist.
"The injury is consistent with having been caused by a bladed object.
"We have recovered a knife and an open packet of co-proxamol tablets at the scene."
He said police inquiries were continuing but there was no indication at this stage of any other party being involved.
Dr Kelly's body was found at 0920 BST in a wooded area at Harrowdown Hill, near Faringdon, after his family had reported him missing on Thursday night.
Tory leader Iain Duncan Smith called on Mr Blair to recall Parliament and broaden the inquiry to investigate the government's handling of intelligence on Iraq.
Dr Kelly disappeared two days after being grilled by the Commons foreign affairs select committee as part of its inquiry into the use of intelligence in the run-up to the war.
He told MPs he had spoken to BBC reporter Andrew Gilligan.
Mr Hoon admitted he warned the committee to "be gentle" with Dr Kelly.
David Kelly gave evidence to MPs earlier this week
"My fear was that for anyone giving evidence to a select committee there is obvious pressure and stress," he told the BBC.
"I wanted to make sure for someone who had not been through that before, that the committee chairman recognised this fact."
Commons foreign affairs committee chairman Donald Anderson defended the questioning by MPs.
"If it was strong, the criticisms appear to be more directed against the Ministry of Defence, rather than against him," he said.
Labour MP Andrew Mackinlay apologised for "any stress" his combative questioning at the hearing had "unintentionally" caused Dr Kelly.
The former Labour minister Glenda Jackson said blame lay with Downing Street, who used a battle with the BBC to divert attention from the failure to find weapons of mass destruction in Iraq.
She said Tony Blair's credibility had been "holed below the waterline" and it was time for him to resign.
Dr Kelly's local MP Robert Jackson said the BBC's role should also be questioned, becuase they failed to confirm that Dr Kelly was the source until after his death.
BBC director of news Richard Sambrook only broke the news on 20 July, after speaking to the family of the Iraq weapons expert who was found dead on 18 July.
The BBC said it was "shocked and saddened" by what had happened to Dr Kelly and extended its "deepest sympathies" to his family and friends.
Dr Kelly is survived by his wife, Janice, and three daughters Sian, 32, and 30-year-old twins Rachel and Ellen.