If true Iran could make enough uranium to have atomic bomb in a year, experts say.
Iran is running more than 3,000 centrifuges used to enrich uranium and is installing more every week, President Mahmoud Ahmadinejad said on Sunday, in comments likely to fuel Western fears Tehran is seeking an atomic bomb.
Western experts say 3,000 machines running smoothly for long periods at supersonic speeds could make enough enriched uranium for an atomic bomb in about a year, if Iran wanted, and form the basis for "industrial-scale" production of nuclear fuel.
But an International Atomic Energy Agency (IAEA) report issued on Friday said Iran remained well short of 3,000 centrifuges and that its rate of enrichment was still far below capacity.
The report also indicated the pace of centrifuge installation had slowed markedly since April, when Ahmadinejad first announced "industrial" capacity.
Iran has repeatedly dismissed talk of a slowdown.
"We have more than 3,000 centrifuges working and every week a new set is installed," Fars News Agency quoted Ahmadinejad as saying. Other Iranian news agencies also carried his comments.
Centrifuges are set up in interlinked networks or "cascades" of 164 machines each.
Iran, the world's fourth largest oil producer, insists its goals are peaceful and says it wants to master technology only to make fuel for a network of atomic power plants it plans.
But Tehran, which hid nuclear work from the IAEA for almost 20 years, has failed to convince big powers of its peaceful intent, and the UN Security Council has imposed two rounds of sanctions since December because Tehran has ignored demands to halt uranium enrichment.
"They [world powers] were thinking that with each resolution the Iranian nation would retreat. But after each resolution the Iranian nation presented another nuclear achievement," Ahmadinejad was quoted as saying.
He said Iran was "united and defiant" behind its atomic aims and had brushed aside ideas of those inside Iran who counselled a softer line. He did not name them but some reform-minded politicians have said Iran should heed UN resolutions.
Ahmadinejad is not the most powerful figure in Iran. Ultimate authority lies with supreme leader Ayatollah Ali Khamenei. But Khamenei has also in the past said Iran would not retreat from its nuclear goals.
Iran has agreed with the IAEA to a rough timetable for addressing lingering concerns about its nuclear activities, a step IAEA chief Mohamed ElBaradei told German weekly Der Spiegel could be Iran's last chance to come clean about its plans.
"By November, or December at the latest, we should be able to see whether the Iranians are sticking to their promises. If they fail to do this, Tehran would be missing a great chance - perhaps its last," ElBaradei said.
The US, which has been leading efforts to isolate its long-time foe, has said Iran must do more than cooperate with the IAEA to avoid a third set of sanctions. It says it must halt enrichment too, a step Iran has repeatedly ruled out.
Washington insists it wants diplomacy to end the standoff but has not ruled out military action if that route fails.