Speaking after Hans Blix's report to the UN security council, in which he called for more time for inspections, the foreign secretary, Jack Straw, told the council that Saddam Hussein should be set a March 17 deadline to comply with UN demands on disarmament or face the prospect of military action.
Mr Straw was tabling an amendment to the draft resolution proposed jointly with the US and Spain which, if adopted, would give Iraq a "further period" to comply with the earlier resolution 1441.
The amendment, which slightly waters down the tough draft resolution that has created a major divide within the UN, proposes that unless the security council decides by March 17 that Iraq has taken its "final opportunity" to disarm, serious consequences will follow.
Its aim is to gain support from undecided members of the 15-nation security council who have grave misgivings about voting for immediate warfare.
But even before Mr Straw spoke, the idea of a deadline was rejected by the French foreign minister, Dominique de Villepin, who told the security council: "We cannot accept an ultimatum as long as inspectors are reporting cooperation."
He said a deadline would be "a pretext for war".
America and Britain's tough stance comes despite Mr Blix's report outlining improved cooperation from Iraq. Thirty-four of Iraq's illegal Samoud 2 missiles had been destroyed, Mr Blix said, despite Baghdad's insistence that the weapons did not violate the UN-mandated 150km limit.
Mr Blix noted that no missiles appeared to have been destroyed today, and expressed hope that this was a temporary delay.
In sharp contrast with US and British claims that Iraq is not disarming, Mr Blix said the destruction of the missiles was a "substantial measure of disarmament".
"We are not talking about the breaking of toothpicks," he said. "These are lethal weapons being destroyed."
Mr Blix said that, in general, his inspection teams had "been able to perform professional, no-notice inspections all over Iraq".
However, he criticised Saddam Hussein's regime for failing to provide documentary evidence of past production of chemical and biological weapons.
The Iraqis had handed over some documents detailing the destruction of anthrax and VX, he said, but that only raised questions about how much had been produced in the first place.
There have been reports of Iraq producing weapons of mass destruction in underground facilities, Mr Blix said, and the inspectors had hunted for these, in some cases using ground radar. No underground facilities for chemical or biological weapons had been found.
Mr Blix also reported progress in attempts to interview Iraqi scientists with knowledge of proscribed weapons programmes.
He said that Iraq had provided the names of "many" relevant scientists, and the UN had requested interviews with 38 of them. Ten had accepted the invitation, with seven saying yes during the last week.
"After a period of somewhat reluctant cooperation, there has been an acceleration in Iraqi initiatives in January," Mr Blix said.
He pointed out at length that weapons inspectors did not just operate under UN resolution 1441, which the security council passed unanimously in November, but under a number of resolutions passed since the 1991 Gulf war.
Several times, he referred to future improvements in inspections, including night vision flights provided by Russia, drone surveillance flights using German aircraft, and potentially out-of-country interviews with key Iraqi personnel.
"Disarmament, and at any rate verification, cannot be instant," he said. "It will not take years, nor weeks, but months."
President Bush in the James S. Brady Briefing Room during the press conference.
During a press conference on Tuesday, President George W. Bush called on veteran White House reporter Helen Thomas for the first time in three years. She asked, "... your decision to invade Iraq has caused the deaths of thousands of Americans and Iraqis, wounds of Americans and Iraqis for a lifetime. Every reason given, publicly at least, has turned out not to be true. My question is, why did you really want to go to war?"

Bush replied, "And when Saddam Hussein chose to deny inspectors, when he chose not to disclose, then I had the difficult decision to make to remove him. And we did, and the world is safer for it."

The exchange has provoked extreme responses in the blogosphere, with conservative commentators like Fred Barnes of Fox News portraying Helen Thomas as being "unprofessional" and "improper" in "accusing the President."

Barnes argued, "Reporters aren't supposed to fire accusations at the President or anybody else they're interrogating, and that was wrong." He pointed out that Helen Thomas is an outspoken critic of the war in Iraq and the Presidency of George W. Bush. Fox News reporter Brit Hume said of Thomas, "She has an agenda, period, and always has had an agenda of sorts." Conservative commentators mostly agreed that President Bush "got the better of the exchange."

Liberal commentators like Josh Marshall from Talking Points Memo focused on the President's response, saying, "Of course, that's not what happened. ... We got the resolution passed. Saddam called our bluff and allowed the inspectors in. President Bush pressed ahead with the invasion."
He added "His lies are so blatant that I must constantly check myself so as not to assume that he is simply delusional or has blocked out whole chains of events from the past."