The prime minister has denied dismissing opponents of action against Iraq as "naive".

Responding to a question from Peter Kilfoyle, a prominent critic of government foreign policy, Tony Blair said: "I do not describe anyone who takes a different view to me on Iraq as 'utterly naive'. What I said would be utterly naive would be to deny that weapons of mass destruction were not an issue."

Iain Duncan Smith earlier urged him to confirm that he would "support and contribute to" military action against Saddam Hussein.

Blair said there "was no doubt at all" that the Iraqi leader was developing weapons of mass destruction but insisted that he would respond in a "calm and measured" way.

"Saddam Hussein has a very clear message from the international community," said Blair. "The weapons inspectors should go back - anyone, any place any time."

Duncan Smith called on the prime minister to state publicly that the British government now wanted to remove Saddam Hussein from office.

"Not only is Iraq developing weapons of mass destruction but is has also become apparent at the moment that it is a major sponsor of terrorism in the Middle East. In the US the prime minister spoke about a 'regime change' in Iraq," he said.

"Given his reported comments can he confirm that getting rid of Saddam Hussein may now be an objective of the government?"

Blair said there was "no doubt" that the world would be safer without the Iraqi regime.

"The people who would rejoice most at the removal of Saddam Hussein from office would be the Iraqi people themselves. We should never forget that this is a regime with a particular record," he said.

"The Iran/Iraq war in which a million people lost their lives, then the annexation of Kuwait which precipitated the Gulf War and then, of course, perhaps the most appalling act of all, the use of chemical weapons on the Kurdish people."

"There is no doubt whatever that the world would be a better place without Saddam. However the method of doing this, this as I say, is open to consultation and deliberation."