French President Nicolas Sarkozy warned Friday that any foreign military intervention against Iran's nuclear programme would trigger "war and chaos" across the Middle East and beyond.
"Time is limited. France will do everything to avoid military intervention, but there is only one way to avoid it: a much tougher, more decisive, sanctions regime," Sarkozy told an audience of diplomats in Paris.
He called on all countries to freeze Iranian central bank assets and halt imports of Iranian oil.
"Those who do not want to reinforce sanctions against a regime which is leading its country into disaster by seeking a nuclear weapon will bear responsibility for the risk of a military breakdown," he warned.
"And I say to our Chinese and Russian friends: Help us guarantee peace in the world ... we clearly need you," he added.
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"A military intervention would not solve the problem but would unleash war and chaos in the Middle East and perhaps, alas, the world," he warned.
France has been one of the loudest Western voices pushing for economic sanctions to force Iran to abandon its nuclear programme, which Paris fears could lead to the Islamic regime developing an atomic bomb.
But it remains opposed to calls from some hawks in the United States and Israel for air strikes against Iranian facilities.
Iran insists its nuclear fuel enrichment programme is designed to produce fuel for reactors in future civilian power stations and for medical isotopes.
Tehran has vowed to defeat any military intervention and has warned that it may attempt to block shipping lanes and choke off oil exports from the Gulf if sanctions target its own energy industry or banks.
Britain and the United States have tightened their economic sanctions while the European Union is to meet next week and is expected to approve new measures against Iranian oil exports and the financial sector.