"The basis of sanctions against Iran are the resolutions of the United Nations Security Council," Plassnik, who is currently visiting Germany, told the Handelsblatt newspaper.

"France is free to slip in changes. We stick to our positions," she said.

Germany too has expressed reservations about France's proposal to press ahead with plans for sanctions independent of the UN framework.

Plassnik also rejected a call by Washington for foreign companies to slash their investments in Iran, irrespective of any decisions taken by the UN.

Austria's OMV, the biggest oil and gas group in Central Europe, signed a memorandum of understanding with Iran in April to jointly develop a gas field in the Gulf. It is already involved in an oil venture there.

But Plassnik stressed that Tehran "has to realise the determination of the international community to ensure that no one wants their atomic weapons."

French Foreign Minister Bernard Kouchner angered Tehran last month when he said the world had to prepare for war over Iran's nuclear programme.

Iran denies it is trying to build the bomb, saying that its programme is aimed at generating fuel for its growing population.

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