TEHRAN, Iran — Iran said yesterday that it has started using new centrifuges that can churn out enriched uranium at more than double the rate of the machines that now form the backbone of the Islamic nation’s nuclear program. The announcement was the first official confirmation by Tehran after diplomats with the United Nation’s nuclear watchdog reported earlier this month that Iran was using 10 of the new IR-2 centrifuges.

“We are [now] running a new generation of centrifuges,” the official IRNA news agency quoted the deputy of Iran’s Supreme National Security Council, Javad Vaidi, as saying. No futher details were provided.

Meanwhile, a senior Iranian official yesterday blamed America for Tehran’s refusal to respond to an International Atomic Energy Agency probe into whether Iran tried to make nuclear weapons in the past. Iran’s chief delegate to the IAEA, Ali Ashgar Soltanieh, claimed information provided by Washington and used by the United Nations agency was fake and it came to Tehran too late for a proper review.

America dismissed the complaint, saying Iran could have answered concerns about its nuclear program years ago.

Tehran insists its nuclear program is intended only to produce energy, but America and some of its allies suspect it could lead to the development of weapons.

Iran is already under two sets of United Nations Security Council sanctions for refusing to suspend uranium enrichment. The five permanent members of the United Nations Security Council and Germany have agreed on a draft resolution for a third set of sanctions. The IAEA highlighted the “new-generation centrifuges” in its latest report on Iran released Friday, but did not provide further details. Earlier this month, diplomats accredited to the IAEA told the Associated Press that 10 IR-2 centrifuges had started processing small quantities of uranium hexafluoride gas in a process that can produce fuel for a nuclear reactor or fissile material for a weapon.

Ten centrifuges are too few to produce enriched uranium in the quantities needed for an industrial-scale energy or weapons program and far below the 3,000 older centrifuges in Iran’s underground enrichment plant in the central town of Natanz.

Friday’s IAEA report said many past questions about Iran’s nuclear program had been resolved but highlighted Tehran’s continued refusal to halt uranium enrichment, paving the way for another set of sanctions.

Iranian President Ahmadinejad said Saturday the report vindicated Iran and called on America and its allies to apologize for accusing Tehran of seeking nuclear weapons. He also warned that Tehran would take unspecified “decisive reciprocal measures” against any country that imposed additional sanctions against Iran.

Most of the material shown to Iran by the IAEA in its investigation of the nation’s alleged attempts to make nuclear arms came from Washington, though some was provided by American allies, diplomats told the Associated Press.

But Mr. Soltanieh dismissed much of the material as false. In any case, he said, it came too late — three years after American intelligence claimed it had material on a laptop computer smuggled out of Iran indicating that Tehran had been working on details of nuclear weapons. “They should have given it to us three years ago,” Mr. Soltanieh said, suggesting Tehran would then have had a more substantive response.