President Bush is expected to tell the UN on Thursday that the US will agree to a return of weapons inspectors to Iraq.
However, this will be only with the proviso that if the first-time inspectors are turned away from a weapons site, this would be an immediate cause for US-led military action .
White House spokesman Mr Ari Fleischer hinted yesterday at the possibility of so-called coercive inspections, in which foreign troops would be prepared to shoot their way into suspected weapons sites if denied access by Iraq.
Mr Fleischer said it appeared there was an international movement toward toughening UN resolutions demanding Iraq give up its suspected stockpile of weapons of mass destruction.
Mr Bush will address the UN General Assembly on Thursday as pressure builds around the world for a return of weapons inspectors rather than unilateral US action against Baghdad.
Mr Bush is reported to be committed to a timetable for action so rapid that he will seek approval from Congress for the use of military force within weeks.
UN Secretary-General Mr Kofi Annan said yesterday he and other world leaders had concerns about possible unintended consequences from the use of force against Iraq. "What sort of Iraq do we wake up to after the bombing, and what happens in the region? What impact would it have?"
He stressed the importance of securing approval for any action from the 15-nation UN Security Council, whose five permanent members - the US, Russia, China, France and Britain - have veto power. The council imposed sanctions on Iraq after its 1990 invasion of Kuwait and authorised international military action.
Denmark's Prime Minister Mr Anders Fogh Rasmussen, whose country holds the EU's presidency, called yesterday for "maximum pressure" on Iraq to allow the return of UN weapons inspectors.
"It's the clear belief of Denmark and the EU that any action taken - which remains hypothetical - must conform to international law. International inspectors must have free and total access to conduct their inspections to determine Iraq's capacity to produce weapons of mass destruction."
Mr Rasmussen spoke with Mr Bush by telephone yesterday. He said he "stressed that if Iraq continues to refuse the UN's demands, possible coercive measures should be carried out based on a mandate from the UN Security Council".
French President Mr Jacques Chirac yesterday proposed a council resolution giving Iraq a three-week deadline to admit and fully co-operate with UN weapons inspectors before considering military force.
Any attempt to oust Mr Hussein without UN backing would be a recipe for chaos in global affairs, Mr Chirac said, adding: "A few principles and a little order are needed to run the affairs of the world...As soon as one nation claims the right to take preventive action, other countries will naturally do the same. If we go down that road, where are we going?"
Mr Bush continued building his case for action against Iraq in a meeting in Detroit yesterday with the Canadian Prime Minister, Mr Jean Chretien. Mr Fleischer said he could report no progress in swaying Mr Chretien.
Mr Bush called several world leaders yesterday to ask them to listen carefully to his UN speech. They included Mr Annan, Mr Rasmussen, President Ahmet Necdet Sezer of Turkey, Egyptian President Hosni Mubarak, Saudi Crown Prince Abdullah and NATO secretary-general Lord Robertson.
Many countries remain extremely critical of US intentions. German Chancellor Mr Gerhard Schröder said yesterday Germany would not "click its heels" and follow the US into war.
Meanwhile, the International Institute of Strategic Studies in London yesterday warned in a report that Iraq could build a nuclear weapon "in a matter of months" if it managed to buy or steal raw materials from outside.