BEIRUT (Reuters) ¿ Despite blunt French talk of possible war with Iran, the United States may for the moment be too entangled in Iraq to turn from diplomatic to military action to curb Tehran's nuclear and regional ambitions.

But General David Petraeus, the US commander in Iraq, said this month his forces were already fighting a "proxy war" with Iran — a murky contest which raises the chances for either side to spark a wider confrontation by mishap or intent.

"There is still some margin for diplomacy on the nuclear issue inside or outside the UN Security Council," said Dubai-based security analyst Mustafa Alani. "But if you look at the tension in the region and at the flashpoints between the Iranians and the Americans, no one should rule out an accidental war."

Tehran blames the US presence in Iraq for destabilising its neighbour and denies Western suspicions that its nuclear programme is military, not just to generate electricity.

The United States accuses Iran of supplying Iraqi and Afghan insurgents with money and weaponry to wear down its resolve, and of backing Lebanese and Palestinian militants who fight Israel. In the same breath, US President George W. Bush now casts the war in Iraq as a struggle against Iran and al Qaeda — whose militant Sunni ideology is anathema to Tehran's Shi'ite leaders.

"If we were to be driven out of Iraq...al Qaeda could gain new recruits and new sanctuaries," he said last week. "Iran would benefit from the chaos and would be encouraged in its efforts to gain nuclear weapons and dominate the region."

Iran has defied diplomatic pressure led by the United States and its European allies to halt uranium enrichment. Major powers are due to meet in Washington on Friday to discuss a third Security Council resolution to toughen sanctions on Tehran.

While not ruling out military options, US officials insist they are pursuing diplomatic means to alter Iranian behaviour.

"This is nonsense, this talk of sabre-rattling, war drums beating," State Department official David Satterfield said.

Yet French Foreign Minister Bernard Kouchner sent shudders around world capitals on Sunday by saying his country should prepare for war, even though this was not an imminent danger.

Iranian President Mahmoud Ahmadinejad dismissed the comments as media fodder that Tehran did not take seriously. Kouchner himself said in an interview published on Tuesday that his words were intended as a "message of peace" underlining the importance of diplomacy. He had, he suggested, been misunderstood.

Russia and China, which like France fiercely opposed the US-led invasion of Iraq, criticised Kouchner's original remarks, as did some European officials anxious to focus on diplomacy at the UN and its nuclear watchdog, the IAEA.

"Before talking about new wars, we need to allow the necessary time for the political and diplomatic initiatives," Italian Foreign Minister Massimo D'Alema cautioned.

In London, a Foreign Office spokesman said Kouchner had actually been stressing the need to avoid war. "There's a lot being stirred up to suggest that the US is moving away from the diplomatic route. We haven't seen that," he added.

A French diplomat said comments by his government were not intended to be bellicose but reflected real worries in Paris that the standoff with Iran could be heading towards conflict.

Washington, with its hands full in Iraq, is likely to steer away from military options for now, unless the Iranians "stumble into something", argued Toby Dodge, a British expert on Iraq.

"Clearly there has been a shift in US rhetoric from the nuclear to the Iraq issue and the 'proxy war', but I see no intention in the next few months to go military," he said. "Full-scale military action would involve a bombing campaign of weeks in duration with massive civilian casualties that would put America's presence in Iraq in jeopardy because the Iranians would kick back in Iraq, across the Gulf and beyond."

This would be a nightmare for Saudi Arabia and other US-allied Gulf oil producers whose desire to see Iran cut down to size is tempered by their fear of chaos and retaliation. Sunni Arab leaders fear Iran's nuclear drive as well as what they see as its meddling in Iraq, Lebanon and Palestinian areas.

"The Saudis don't trust the Americans to take military action against Iran after the experience in Iraq," Alani said. "They aren't sure how they will handle the Iranian revenge."

In Iran, any US assault would provoke a nationalist surge, even if some Iranians might blame the war on their politicians, said Hamidreza Jalaiepour, a Tehran university professor.

"If Iranians feel they are under foreign attack, a new nationalism will emerge," he said.

For now, Iranian leaders are exuding confidence that US commitments in Iraq and Afghanistan preclude military action.

Judging by Kouchner's words and the alarm they aroused, the world is far from sharing Tehran's conviction.