Prime Minister Tony Blair last night threatened military action to topple Iraqi president Saddam Hussein's "brutal" regime.

Mr Blair pledged there would be no "precipitive action" but delivered a blunt warning to Saddam that he had to allow weapons inspectors back into his country "any time, any place that the international community demands".

The Prime Minister's toughest talk yet on Iraq came in a speech at the George Bush Senior Presidential Library in College Station, Texas, after two days of talks with the present President, George W Bush.

"We must be prepared to act where terrorism or weapons of mass destruction threaten us," he said.

"The fight against international terrorism is right. We should pursue it vigorously, not just in Afghanistan but elsewhere. Since September 11 the action has been considerable, in many countries, but there should be no let up.

"If necessary, the action should be military and again, if necessary and justified, it should involve regime change. I have been involved as British Prime Minister in three conflicts involving regime change - Milosevic, the Taliban and Sierra Leone, where a country of six million people was saved from a murderous group of gangsters who had hijacked the democratically-elected government."

Mr Blair said the international community could not intervene in all cases "but where countries are engaged in the terror or weapons of mass destruction business, we should not shirk from confronting them".

Mr Blair said he hoped that Syria, Iran and North Korea could be persuaded to reform.

But he went on: "As for Iraq, I know some fear precipitive action. They needn't. We will proceed, as we did after September 11, in a calm, measured, sensible but firm way.

"But leaving Iraq to develop weapons of mass destruction in flagrant breach of no less than nine separate United Nations Security Council resolutions, refusing still to allow weapons inspectors back to do their work properly, is not an option.

"The regime of Saddam is detestable, brutal, repressive, political opponents routinely tortured and executed.

"It is a regime without a qualm in sacrificing the lives of its citizens to preserve itself, or starting wars with neighbouring states and it has used chemical weapons against its own people.

"The moment for decision on how to act is not yet with us. But to allow weapons of mass destruction to be developed by a state like Iraq without let or hindrance would be grossly to ignore the lesson of September 11 and we will not do it.

"The message to Saddam is clear: he has to let the inspectors back in - anyone, any time, any place - that the international community demands."

Mr Blair, who had lunch with the former President Bush before delivering his address, also underlined his message on the Middle East calling for an end to violence from all sides so a new political peace process could begin.

He said: "The plight of the Middle East would make the hardest heart break."

But Mr Blair's central message was plain. He said: "If the world makes the right choices now, at this time of destiny, we will get there. And Britain will be at America's side in doing it."