"We have to prepare for the worst, and the worst is war," he said in an interview broadcast on French television and radio.

"We must negotiate right to the end," with Iran, he said, but underlined that if Tehran possessed an atomic weapon, it would represent "a real danger for the whole world."

Calling the nuclear standoff "the greatest crisis" of present times, the minister said: "We will not accept that the bomb is manufactured," and hinted that military plans were on the way.

"We are trying to put in place plans which are the privilege of chiefs of staff and that is not for tomorrow," he said but stressed that although any attack on Iran was far from taking place, "It is normal for us to plan" for any eventuality.

In Washington, US Defense Secretary Robert Gates took a more muted approach on Sunday.

"I will tell you that I think the administration believes at this point that continuing to try and deal with the Iranian threat ... through diplomatic and economic means is by far the preferable approach," he said.

Kouchner meanwhile said France wanted the European Union to prepare sanctions against Iran, outside the ambit of the UN Security Council, to force Tehran to forsake its nuclear ambitions.

"We have decided that while negotiations are continuing ... to prepare eventual sanctions outside the ambit of UN sanctions. Our good friends, the Germans, suggested that," he said.

The foreign minister also said leading French companies such as Total and Gaz de France had been urged not to undertake new work or contracts in Iran.

Tehran vehemently denies Western allegations it is seeking an atomic weapon, saying its nuclear drive is aimed at providing electricity for a growing population whose fossil fuels will one day run out.

The five permanent Security Council members -- Britain, China, France, Russia and the United States -- plus Germany are due to meet to discuss a new draft UN resolution on sanctions against Iran on September 21 in Washington.

In the free-wheeling interview, Kouchner also touched upon the criteria for new members aspiring to join the European Union such as Turkey, saying French President Nicolas Sarkozy favoured the scrapping of a mandatory referendum on future adhesions.

"I do not fear revealing this secret. I think the president wants this as well," he said.

France has put the brakes on Turkey's membership talks but Sarkozy has said he would not block the discussions if a group of "wise men" was established by 2009 to debate the goals and ambitions of the EU over the next two decades.

Turkey began EU accession negotiations in October 2005 but it has only managed to open four of the 35 chapters, or policy areas, that all candidates must complete to join.

Croatia, which began talks the same day, has opened 12.

Turkey's talks are expected to last at least a decade, with no guarantee of membership at the end of it all. The process has been hampered by Ankara's refusal to open its ports and airports to Greek Cypriot ships and planes.

related report
Iran's Ahmadinejad defiant amid nuclear warnings
President Mahmoud Ahmadinejad on Sunday declared Iran had mastered nuclear technology and would never yield in the face of international pressure over its atomic drive.

Ahmadinejad's comments in an interview with Iranian television were broadcast hours after French Foreign Minister Bernard Kouchner warned the world should brace for war over Iran, although he did not react to those remarks.

"Of course we will not step back," said Ahmadinejad in the interview with Iran's Farsi language international channel Jam-e Jam in response to a call-in question by a viewer.

"We have mastered the technology to enrich uranium and we have arrived at an industrial stage," he added.

"The West are talking about imposing sanctions on us. But they cannot do this," he added.

The Iranian leader repeated a demand for a public debate with US President George W. Bush to "discuss important global issues with the aim of resolving them."

"I had already suggested this the previous year. I am going to New York. Let us sit down together and hold discussions. But not behind closed doors. I have suggested that we discuss these global issues at the UN General Assembly to resolve them.

"Our aim should be to resolve these global issues. I want him to spell out his position and I will outline mine. There, the representatives of the 200 countries can evaluate them," he said.

Ahmadinejad said there could then be a "global referendum" on the positions outlined by the two sides.

He also rejected any direct negotiations between Tehran and Washington.

The UN Security Council has issued two sanctions resolutions against Tehran for its refusal to suspend uranium enrichment, a process that can be used to make nuclear weapons, and Western powers have warned of more action.

The United States has never ruled out using military strikes to punish Iran for its defiance and Defense Secretary Robert Gates said Sunday that "all options are on the table."

France's Kouchner said in a television interview also Sunday: "We have to prepare for the worst, and the worst is war."

Iran vehemently denies allegations it is seeking an atomic weapon, saying its nuclear drive is aimed at providing electricity for a growing population whose fossil fuels will one day run out.

related report
US says 'all options' on table with Iran, but prefers diplomacy
The United States will stick to diplomatic and economic pressure to force Iran to halt its nuclear drive, but "all options are on the table," Defense Secretary Robert Gates said Sunday.

Interviewed on Fox News, Gates also said the United States would have a "real problem" if Syria and North Korea are collaborating on a nuclear program, but refused to confirm reports to that end.

Asked if President George W. Bush would consult Congress before launching any strikes on Iran, Gates said he would not be drawn on "hypotheticals."

"I will tell you that I think the administration believes at this point that continuing to try and deal with the Iranian threat ... through diplomatic and economic means is by far the preferable approach," he said.

Iran vehemently denies Western allegations it is seeking an atomic weapon, saying its nuclear drive is aimed at providing electricity for a growing population whose fossil fuels will one day run out.

"We always say all options are on the table," Gates said. "But clearly, the diplomatic and economic approach is the one we're pursuing."

The five permanent Security Council members -- Britain, China, France, Russia and the United States -- plus Germany are due to meet to discuss a new draft UN resolution on sanctions against Iran on September 21 in Washington.

"We have to prepare for the worst, and the worst is war," French Foreign Minister Bernard Kouchner said Sunday in an interview broadcast on French television and radio.

"We must negotiate right to the end," he said, but underlined that if Iran possessed an atomic weapon, it would represent "a real danger for the whole world."

The United States has never ruled out taking military action against Iran but on Friday, Iran's supreme leader Ayatollah Ali Khamenei brushed off the notion that it could now threaten the Islamic republic.

He said that Bush had been defeated in his Middle East plans and would one day stand trial for "atrocities" committed in Iraq.

The US and Iranian envoys to Baghdad have held two rounds of landmark talks in Baghdad on Iraqi security this year, but Khamenei's comments underlined the degree of enmity that remains between the two sides just on this issue.

Washington also accuses Iran of providing sophisticated weaponry to Shiite militias in Iraq, and Syria of turning a blind eye to infiltration of its borders by Sunni insurgents, charges both governments deny.

Announcing a limited pullout of troops from Iraq on Thursday, Bush demanded that Iran and Syria end attempts to "undermine" the government of insurgency-wracked Iraq.

The top US commander in Iraq, General David Petraeus, last week accused Iran of fighting a "proxy war" in Iraq through the covert operations unit of its elite Revolutionary Guards.

But the Pentagon chief ruled out using US forces to chase Shiite extremists in Iraq over the Iranian border.

He said "the general view is we can manage this problem through better operations inside Iraq and on the border with Iran -- that we can take care of the Iranian threat ... inside the borders of Iraq."

Gates refused to confirm the veracity of leaked intelligence reports suggesting that North Korea may be helping Syria build a nuclear weapons facility.

"But all I will say is we are watching the North Koreans very carefully. We watch the Syrians very carefully," he said.

If North Korea were flouting its UN obligations to disarm its nuclear program and Syria were pursuing weapons of mass destruction, "I think it would be a real problem," Gates added.

Both Syria and North Korea have dismissed the reports of nuclear collaboration, after foreign media reports that Israeli warplanes had launched an air strike on a possible joint nuclear project on September 6.

Gates declined to comment on the Israeli raid, which US and British newspapers say could have been intended to destroy a nuclear facility in northeast Syria staffed by North Korean technicians.