The tough talk from Paris came as the five permanent members of the UN Security Council plus Germany prepared to discuss new UN sanctions on Iran, which has failed to respond to demands to stop enriching uranium.

French Foreign Minister Bernard Kouchner met his Dutch counterpart Maxime Verhagen in Paris and said European countries should prepare their own sanctions programmes outside the orbit of the UN.

"These would be European sanctions that each country, individually, must put in place with its own banking, commercial and industrial system. The English and the Germans are interested in talking about this. We will try to find a common European position," Kouchner said.

Verhagen said the "first effort should be to convince the Security Council to apply more sanctions. But when the Security Council doesn't agree, I am prepared, I am willing, to apply European Union sanctions in common with the United States sanctions."

France has taken a more threatening posture towards Iran since the election of President Nicolas Sarkozy in May, and its willingness to promote extra-UN sanctions puts it closely in line with the position of the United States.

On Sunday, Kouchner used the toughest language to date from a French minister, warning that "we have to prepare for the worst, and the worst is war." If Tehran possessed an atomic weapon, it would be a "real danger for the whole world," he said in an interview.

The remarks drew immediate condemnation from Tehran, where the state-owned IRNA news agency said that Paris was pandering to Washington.

"The new occupants of the Elysee (presidential palace) want to copy the White House," it said, accusing Sarkozy of taking on "an American skin."

French Prime Minister Francois Fillon said Monday tensions over Iran's nuclear programme were "extreme" but insisted there was still room for diplomacy.

"The Iranians must understand that tension has reached an extreme point... in the relationship between Iran and its neighbours," Fillon said, while adding that "a confrontation with Iran is the last option that any political leader would want."

Some of France's own European neighbours reacted nervously to Kouchner's strident tones, with Austrian Foreign Minister Ursula Plassnik criticising his "martial rhetoric".

"I am for continued work towards a negotoiated solution," she said in Vienna where the International Atomic Energy Agency (IAEA) was convening for its annual meeting with Iran top of the agenda.

In France the opposition Socialist Party leader Francois Hollande called on Sarkozy and Kouchner to spell out more clearly what French policy is on the Iranian nuclear programme.

"To say that we have to prepare for the worst, in other words war, means that the government and the president have information which tends to the conclusion that Iran is moving towards the atomic bomb and negotiations are stuck," he said, calling on Sarkozy to address the nation.

Commentators said the tougher French policy on Iran was part of a pattern which has also seen greater accommodation with the United States over Iraq, Turkish entry to the EU, and NATO.

"Both in content and in appearance things are shifting, and France is more in phase with US policy. It is not a question of alignment, but of convergences -- especially on the Iranian issue," said Bruno Tertrais of the Foundation for Strategic Research in Paris.