LONDON - U.S. Secretary of State Hillary Clinton said on Sunday that international powers would not wait forever for Iran to prove it was not developing nuclear bombs.
British foreign minister David Miliband, whom Clinton met in London, said Iran would never have a better opportunity to establish normal ties with the rest of the world but that it had to start behaving like a normal country.
Iran agreed at a meeting with six world powers in Geneva on October 1 to allow U.N. experts access to a newly disclosed uranium enrichment plant near the city of Qom.
Clinton said the meeting was a constructive beginning but added that it had to be followed by action.
The international community will not wait indefinitely for evidence that Iran is prepared to live up to its international obligations, Clinton said at a news conference.
Iran suggested on Sunday that it may embark on further refining of uranium -- comments likely to add to concern among Western powers, which suspect Tehran is seeking to develop nuclear bombs. Iran denies the charge.
Negotiations are due on October 19 in Vienna on a proposal to send Iranian uranium abroad for processing and then return it to Tehran.
The Islamic state has repeatedly rejected demands to halt its sensitive nuclear work, despite three rounds of U.N. sanctions since 2006.
Progress in the Geneva talks was seen as heading off calls for an immediate round of tougher sanctions in the near future.
Britain and the United States are part of a group of six world powers seeking to defuse the row with Iran over its nuclear program. Miliband said Iran had to earn the right to be trusted on its nuclear program.
I think that Iran's history of covert, secret programs ... explains why the international community does not have confidence in the Iranian regime's protestations about the purely peaceful aspects or purely peaceful purposes of their nuclear program, he said.
Clinton criticized the Iranian leadership for the way it had handled protests over a presidential election in June.
With Iran it is tragic that a country with such a great history, with so much to give to the rest of the world, is so afraid of their own people, she told reporters.
The way that they are utilizing secret prisons, and detentions and show trials, is a reflection of the discontent that they know people feel toward the current leadership.
Her comments follow a report on Saturday that an Iranian court has sentenced three people to death over street unrest that erupted after the election in June and links to exiled opposition groups.
ISNA news agency, citing the head of the publication relations office of the Tehran provincial court, did not identify those condemned, giving only their initials.
It was the first official statement of death sentences in connection with the presidential poll, which the opposition says was rigged to secure hardline President Mahmoud Ahmadinejad's re-election, and the huge opposition protests that followed.
(Additional reporting by Keith Weir in London and Fredrik Dahl in Tehran; writing by Keith Weir; editing by Michael Roddy)