The prime minister has backed president Bush in warning that there are links between al Qaeda and the Iraqi regime.

Blair's comments came after the president said Saddam Hussein "aids and protects terrorists".

"We do know of links between al Qaeda and Iraq, we cannot be sure of the exact extent of those links," Blair told MPs.

Iain Duncan Smith had challenged the prime minister to say whether the defence secretary was right to dismiss reported links between Baghdad and Osama bin Laden's terror network.

Calling for the government to "speak with a clear and consistent voice", Iain Duncan Smith urged the prime minister to publish UK intelligence on the issue.

The Tory leader said the government had a duty to inform the public about scale of the terror threat to the UK.

"They want to know more detail about the potential threat that he poses to this country and our citizens," said Duncan Smith.

"President Bush is preparing to reveal more what his intelligence services know about Saddam's weapons programme and his terrorists links.

"Does he accept that the British people deserve to be given the fullest possible information on the scale and the nature of the threat that we now face?"

Blair insisted that the public would be kept informed, but warned against attempting to divide international opinion.

"Of course we have got to give people the fullest possible information. It is extremely important that people understand exactly what that threat is," he said.

"If Saddam Hussein is allowed to carry on developing weapons of mass destruction, chemical, biological and potentially nuclear weapons, he not just a threat to his own region he is a threat to the world.

"But I really see no point in trying to pose differences between ourselves and the United States when the purpose of what we are doing is to unite the international community around the United Nations position set out in resolution 1441."

Liberal Democrat leader Charles Kennedy also quizzed the prime minister on Iraq.

He asked Blair to say whether "British troops will be infiltrated into the US command structure".

Blair dismissed the argument that the US was in the driving seat - and pointed out that British troops had served as part of joint forces before.

Kennedy said that the US would decide if war would go ahead and deliver the orders to British troops.

"At the end of the day the decisions in all of this are going to be taken by president Bush," he claimed.

Blair said that any decisions about war with Iraq would be decided by "our government, our parliament".

And he challenged the Liberal Democrats to support putting maximum pressure being put on Saddam Hussein to comply with the UN mandate.

Blair argued that the Blix report had concluded that Iraq was not co-operating fully with the UN's demands.

He said MPs should "combine as a House" to put pressure on Saddam rather than put out a "signal of weakness".