PARIS -- France accused Iran yesterday of secretly making nuclear weapons, in a statement that ran counter to Europe's traditional diplomatic caution, and that reflected growing exasperation with Tehran.
Iran denied the allegation by the French foreign minister, Philippe Douste-Blazy, who hardened the line that European negotiators had taken in efforts to persuade Iran to suspend nuclear activities.
''No civilian nuclear program can explain the Iranian nuclear program. It is a clandestine military nuclear program," Douste-Blazy said on France-2 television.
''The international community has sent a very firm message in telling the Iranians to return to reason and suspend all nuclear activity and the enrichment and conversion of uranium, but they aren't listening to us."
Uranium enrichment can produce fuel for both nuclear energy and nuclear weapons. Iran resumed small-scale uranium enrichment last week, but insisted that its nuclear activity was aimed solely at generating electricity.
While the United States has long accused Iran of seeking nuclear weapons, European leaders had been more delicate.
France's Foreign Ministry said Douste-Blazy's remarks were in line with the European position on Iran. France, Germany, and Britain have been negotiating with Iran, but no other European leader has spoken so frankly.
The German chancellor, Angela Merkel, in contrast, said yesterday that she was ''very optimistic that we can do everything to solve this conflict with diplomatic means."
The British foreign secretary, Jack Straw, also struck a cautious note.
''There are strong suspicions internationally that Iran may be seeking to use its nuclear program in order to develop a nuclear weapons capability," he said yesterday while on a visit to Algeria. ''We do not have absolute proof."
The UN Security Council will consider Iran's nuclear activities next month. The council has the power to impose economic and political sanctions on Iran.
''Now it's up to the Security Council to say what it will do, what means it will use to stop, to manage, to halt this terrible crisis of nuclear proliferation caused by Iran," Douste-Blazy said.
Iran's chief negotiator, Ali Larijani, lashed back.
''I recommend that Mr. Douste-Blazy speak in diplomatic terms and avoid increasing tension," Iranian state-run television quoted him as saying. ''The motivation of the French foreign minister behind his new comments is ambiguous to us. But it is in the interests of the region that the West adopts a logical stance toward Iran's nuclear activities."
Georges Le Guelte, a nuclear specialist at France's Institute for International and Strategic Research, called Douste-Blazy's statement ''remarkable."
''It was not very diplomatic," he said, adding that it had sent a powerful message of caution to French companies operating in Iran.
Richard Whitman of the Chatham House think tank in London said Douste-Blazy's comments reflect ''a sense of exasperation with the Iranian government."
''All of the doors that were open in terms of negotiations . . . are gradually being closed by the Iranians," he said.