The United States says it is beginning to win the argument for tougher action against Iraq.

"It does appear that the movement is budding to put some force into previous UN resolutions," President Bush's spokesman, Ari Fleischer, said on Monday.

"Don't take it as military force necessarily," he added.

UN weapons inspectors have been barred from Iraq

He was speaking after French President Jacques Chirac proposed a two-stage plan that could lead to UN authorisation of military force against Iraq.

Mr Bush has, in the meantime, been pursuing his campaign of diplomacy aimed at winning support for his policy of toppling Iraqi leader Saddam Hussein.

He has been meeting Canadian Prime Minister Jean Chretien in Detroit for a summit at which the issue was expected to dominate.

The meeting came within hours of the publication of a report from an independent think-tank that says Iraq could produce a nuclear weapon within months.

The London-based International Institute for Strategic Studies says that Saddam Hussein would first need to obtain supplies of radioactive material.

It also concludes that Iraq has probably been successful in hiding large stockpiles of chemical and biological weapons from UN inspectors, as well as a small number of long-range missiles.

Mr Bush's meeting with Mr Chretien was originally arranged to allow the two leaders to discuss border security.

The key topic, however, is expected to be Iraq. Canada, a staunch ally of the United States, has made no secret of the fact that it is opposed to unilateral action against Iraq.

It believes that the UN and its weapons inspectors have a role to play in trying to stop Iraq's biological, chemical and nuclear programmes.

European opposition

This is similar to the stance of President Chirac, who on Monday reiterated his strong opposition to any unilateral US attack on Iraq.

Mr Chirac instead proposed a two-stage process, beginning with a UN Security Council resolution giving Baghdad three weeks to readmit arms inspectors.

If the inspectors were not let in, the French president said, there could be another resolution backing the use of force.

BBC Washington correspondent Justin Webb says Mr Chirac's comments - which were made in a New York Times interview - appear to represent a watering down of France's previous opposition to US plans.

The French president's comments reposition France closer to Washington than Germany, which has dismissed military intervention in Iraq as an "adventure" in which Berlin will not take part.

Among European nations, only Britain has offered uncritical support to the US.

On Thursday, Mr Bush is due to address the UN General Assembly.

The Vatican has now intervened in the debate, demanding UN authorisation for any strike.

Any action "must be part of a decision taken within the framework of the United Nations," the Vatican's Foreign Minister, Archbishop Jean-Louis Tauran, said in comments to appear in Tuesday's edition of the Roman Catholic newspaper Avvenire, Reuters news agency reports.