"If we don't get an encouraging response from the Iranians, we will have to show firmness, resort to sanctions as in the past," Jean-Pierre Lacroix told AFP.

Asked about a reported Tuesday deadline for a positive response from Tehran, he replied: "We'll have to discuss collectively as we did in the past... We are in an assessment phase for the time being."

Lacroix said the French foreign ministry was due to issue a statement on the case shortly.

Meanwhile Belgium's UN Ambassador Jan Grauls, who took over the rotating presidency of the Security Council this month, said the 15-member body was not planning to take up the Iranian nuclear dossier for now.

Earlier Monday, EU foreign policy chief Javier Solana held what a spokesman described as "inconclusive" talks with Iran's top nuclear negotiator, Saeed Jalili, after Tehran missed a deadline to respond to the compromise offer.

A US State Department spokesman said senior diplomats from the United States, Britain, France, Germany, Russia and China discussed developments by phone Monday and agreed to push for new action if Iran continues holding out.

Solana presented an offer of economic and trade incentives from the six powers in mid-June, while Iran has put forward its own proposal, an all-embracing package of suggestions to resolve the problems of the world, including the nuclear issue.

Iran has so far been hit by three sets of Security Council sanctions for failing to comply with demands that it halt uranium enrichment, a process which produces fuel for nuclear power plants and can also be used to make the fissile core of an atomic bomb.

The United States and its ally Israel, which are leading the international campaign against Iran, have not ruled out military action.

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