The Labour government's popularity with voters has dropped over the handling of the affair and the failure to find any banned weapons in Iraq months after Saddam Hussein's overthrow.
The newly released documents, which give a fascinating insight into the innermost workings of government, showed Blair's communications chief Alastair Campbell urged his boss to become more combative with critics who had opposed going to war.
"MORE COMBATIVE"
"As to the manner in which you deal with it, it must be calm, confident, explanatory and thorough," Blair's right-hand man told the prime minister in a briefing note dated June 3.
"But when you go on to the broader issues, in particular reporting back on Iraq, I think you should display a more combative approach," Campbell said.
"The aim of our opponents is to contaminate the success you had as a war leader in Iraq," Campbell wrote. "The media, particularly the BBC, are trying to create a 'no smoke without fire' atmosphere."
The note was written just days after a BBC journalist's report that the government had "sexed up" a dossier on Iraqi weapons.
Senior judge Lord Hutton's probe into the death of Kelly, identified as the source of the BBC reporter's accusation, has already proved problematic for Blair.
It revealed his chief of staff believed the dossier contained no proof of a threat from Saddam and that a string of Blair aides made suggestions to make it more hard-hitting.
It also showed a senior defence intelligence official told Kelly not to air his doubts over the most dramatic statement in the dossier -- that Iraq could deploy chemical and biological weapons at 45 minutes' notice.
The inquiry was told Hoon intervened to limit the scope of questions Kelly would face at a parliamentary hearing.
- REUTERS
Hutton inquiry website
British Parliament Foreign Affairs Committee transcript:
Evidence of Dr David Kelly
Key players in the 'sexed-up dossier' affair
Herald Feature: Iraq
Iraq links and resources