PARIS (Reuters) - French Foreign Minister Bernard Kouchner said on Sunday his country must prepare for the possibility of war against Iran over its nuclear program, but he did not believe any such action was imminent. Seeking to ratchet up the pressure on Iran, Kouchner also told RTL radio and LCI television that the world's major powers should use further sanctions to show they were serious about stopping Tehran getting atom bombs, and said France had asked French firms not to bid for tenders in the Islamic Republic. "We must prepare for the worst," Kouchner said in an interview, adding: "The worst, sir, is war." Asked about the preparations, he said it was normal to prepare for various eventualities. "We are preparing ourselves by trying to put together plans that are the chiefs of staff's prerogative (but) that is not about to happen tomorrow," he added. Tehran insists it only wants to master nuclear technology to produce electricity, but it has yet to comply with repeated U.N. demands that it suspend uranium enrichment and other sensitive work that could potentially be used in producing weapons. Kouchner's comments follow a similarly hawkish statement by French President Nicolas Sarkozy, who said last month in his first major foreign policy speech since taking office that a diplomatic push by the world's powers was the only alternative to "an Iranian bomb or the bombing of Iran." Asked if France was involved in any planning towards war, he said: "The French army is not at the moment associated with anything at all, nor with any maneuver at all." "PEACE IS IN YOUR INTEREST" France has said repeatedly it wants the U.N. Security Council to pass tougher sanctions against Iran over its failure to dispel fears that it is secretly pursuing nuclear weapons. "We do not want to signal anything other than 'peace is in your interest, and in ours too,"' Kouchner said, adding that the door should be left open to negotiations with Tehran, but Paris has made a suspension of nuclear work a condition for talks. The United States, Germany, France and Britain have led a diplomatic drive to punish Iran for refusing to halt its uranium enrichment program. They succeeded in persuading reluctant Russia and China to back two U.N. sanctions resolutions. Iranian President Mahmoud Ahmadinejad said Tehran would not give up its nuclear program. "Of course we will not abandon our right to nuclear technology," he told state television. "They (the West) talks about imposing sanctions on Iran, but they can not do it." Washington says the time has to expand the penalties and has called a September 21 meeting of the six powers to discuss a third sanctions resolution to submit to the U.N. Security Council. Kouchner said France had asked its biggest companies, including oil giant Total and gas firm Gaz de France, not to bid for projects in Iran. "We have already asked a certain number of our large companies to not respond to tenders, and it is a way of signaling that we are serious," Kouchner said. "We are not banning French companies from submitting. We have advised them not to. These are private companies. But I think that it has been heard and we are not the only ones to have done this." In addition, Paris and Berlin were preparing possible European Union economic sanctions against Tehran, Kouchner said. "We have decided to ... prepare ourselves for possible sanctions outside the U.N. sanctions and which would be European sanctions. Our German friends proposed it. We discussed it a few days ago," Kouchner said.