The Prime Minister insisted during a lengthy appearance before Commons committee chairmen that the conflict was legally justified and that recent remarks by David Kay, head of the Iraq Survey Group, had strengthened that view.

For the first time Mr Blair accepted that the hunt for weapons in Iraq had so far proved a failure. “This is something I have to accept and it is one of the reasons why I think we now need a new inquiry. It is true David Kay is saying we have not found large stockpiles of actual weapons.”

He denied that Mr Kay had said that there was no weapons of mass destruction (WMD) programme or capability or that Saddam was not a threat. He quoted at length from Dr Kay’s remarks last week, saying that he had detailed breach upon breach of UN resolutions by Saddam.

Mr Blair added: “He goes on to say that he has found ample evidence both of breaches of UN resolutions and WMD programmes and capability.

“He actually believes that Iraq was possibly a more dangerous place than we thought, that the conflict was justified and that if we had refused to go to conflict, then the security of the world would be at risk.

“I think it’s as well that the whole of his evidence is taken, not simply one part of it.”

Mr Blair rejected a suggestion from Donald Anderson, chairman of the Foreign Affairs Committee, that he should not have based his evidence for war wholly on the flimsy evidence of WMD. “I don’t regret it and neither do I regret the action that we took,” he said. Failure to act on the intelligence received would have been “a gross dereliction of duty”. He added that a failure to discover weapons did not undermine the legal basis for war, which was the breach of UN resolutions.

Mr Blair said that whatever the investigation found, critics would continue to call for fresh inquiries until one concluded that war was not justified.

He added: “I simply say to people that this threat of the interaction of unstable, chaotic states with weapons of mass destruction and terrorism is the security theat of the 21st century. And, if we were not prepared to deal with it in relation to Iraq with all the history of UN resolutions, with the history of actually using weapons of mass destruction, we would never be making the progress we are today with Iran, with North Korea, with Libya, with other countries where we are able to deal with this issue.”

The Prime Minister insisted that the threat from al-Qaeda would have been greater if military action had not been taken against Iraq. He said: “Irrespective of the weapons being found, the evidence is clear from the Iraq Survey Group that Saddam Hussein was developing programmes for weapons of mass destruction and had every intention of making sure those programmes were developed still further if he was given the chance to do so.

“That would constitute a far greater threat in terms of al-Qaeda than their attempt to cause terrorism in Iraq at the moment, terrible though it is.”

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