Tony Blair, responding to an inquiry into flawed British intelligence on Iraq's banned weapons, told parliament on Wednesday: "No one lied."
"No one made up the intelligence. No one inserted things into the (September 2002) dossier against the advice of the intelligence services," he added.
A long-awaited report by former top civil servant Lord Butler concluded that Britain's intelligence on Iraq's armaments had "serious flaws" but apportioned no blame to any one individual, Blair or otherwise.
Blair admitted it was increasingly unlikely any banned weapons would be found.
"I have to accept, as the months have passed, it seems increasingly clear that at the time of invasion Saddam did not have stockpiles of chemical or biological weapons ready to deploy," Blair said.
The premier repeated his recent justification for war, that he genuinely thought Saddam posed a threat and the world was a safer place for his removal.
"For any mistakes made, as the report finds, in good faith I of course take full responsibility, but I cannot honestly say I believe getting rid of Saddam was a mistake at all," he said.
"The evidence of weapons of mass destruction (WMD) was indeed less certain, less well-founded, than was stated at the time"
The notorious UK dossier from September 2002 said some WMDs could have been fired within 45 minutes of an order to do so.
Yet more than a year since former Iraqi president Saddam Hussein was ousted, no WMDs have been found.
Butler said that assertion should not have been included without heavy qualification.
Evidence of Iraq's alleged weapons of mass destruction was "less certain, less well founded," than he had stated before the war.
"The evidence of weapons of mass destruction was indeed less certain, less well-founded, than was stated at the time," he said.
Blair was addressing parliament an hour after an official inquiry condemned as unreliable much of the British intelligence on Iraqi weapons before the war to remove Saddam.