Iraq's failure to allow UN inspections of its weapons programme is indicative of a growing threat to the West, according to the prime minister.

Tony Blair told MPs on Tuesday that the lesson of September 11 was that it was better to act sooner rather than later to tackle security threats.

But he repeated that there were "no plans" to strike at Saddam Hussein.

With reports indicating that the US is stepping up planning for a military strike on Iraq, the prime minister declined to guarantee that MPs would be given the chance to vote for or against any British involvement.

"I think we've got to decide that at the time really," he said.

However, he promised to "keep the House very closely involved" in any decision.

Documents on the threat posed by Iraq - similar to the dossier published on al Qaeda's involvement in the September 11 terror attacks - may be published to mobilise public opinion behind any military action.

"The only reason we haven't published some of this documentation before is you've got to chose your time for this otherwise you send something rocketing up the agenda when its not necessarily there."

Blair said that while Bill Clinton was arguably in favour of regime change in Iraq, the Bush administration was taking a different approach to implementing the policy.

"The issue of Iraq and weapons of mass destruction is on the agenda in a different way," Blair said.

Emphasising that no decisions had been made on any military action to depose Saddam Hussein, the prime minister said "there's no doubt that this is an issue that should be dealt with".

Saying there was no evidence linking the Iraqi president to the September attacks, he said there were "various rough linkages" between Iraq and al Qaeda.

But he said the issue with Iraq was weapons of mass destruction - not the events of September 11.

"It is clear that Saddam Hussein is still trying to develop weapons of mass destruction," he said.

Blair said the failure of negotiations to allow UN inspectors resume their inspections meant "over a period of time you are entitled to draw the conclusion that this threat is growing not diminishing".

"If there is a gathering threat or danger let us deal with it before it materialises rather than afterwards," he added.

In a move that will be welcomed by critics of the Bush administration's approach, the PM said any military action should be in accordance with international law.

"I certainly agree that we should act, as I hope this country always does, in accordance with international law," said Blair.

The prime minister said Britain's strategic relationship with America meant the two countries would continue to work closely, not just on Iraq but in areas like Russian's inclusion in Nato structures.

Questioned on potential threats to Britain, he said you get a "vast amount of intelligence" continuously flowing in to government and it could be difficult to pick out what should be treated most seriously.

Blair also said he had learned from his experiences of crisis management during the Kosovo campaign, foot and mouth, and the fuel crisis.

"You have to have very strong central command if you're to deal with a major crisis...there's no other way of dealing with it," he told MPs.

"You've got to put aside the normal bureaucracy and thinking...you've got to be prepared to put the rules to one side."

Blair also dismissed suggestions that British intelligence services should be made more accountable to parliament.

"The system works well for the country and I'm just wary about changing it to a system that might not work so well for the country," he said.