Iran is once again building centrifuges that can be used to make nuclear weaponry, breaking the U.N. nuclear watchdog agency's seals on the equipment in a show of defiance against international efforts to monitor its program, diplomats said Tuesday.
Iran has not restarted enriching uranium with the centrifuges -- a step that would raise further alarm. But the resumption of centrifuge construction is likely to push European nations, which have been seeking a negotiated resolution, closer to the United States' more confrontational stance.
The United States accuses Tehran of seeking to develop nuclear weapons and wants the U.N. Security Council to take up the issue. Iran denies the charge and says the centrifuges are part of a nuclear program aimed only at producing energy.
Senior diplomats from France, Britain and Germany are scheduled to meet with Iranian officials this week in London.
Under international pressure last year, the Islamic republic agreed to stop enriching uranium and stop making centrifuges, in a deal reached with the three European nations.
But the moratorium ended several weeks ago, when Tehran -- angry over international perusal of its nuclear program -- broke seals placed on enrichment equipment by the International Atomic Energy Agency, the diplomats said on condition of anonymity.
Iranian officials then resumed assembling and installing centrifuges, which can enrich uranium fuel for generating power or developing warheads, the diplomats said.
It is unclear whether Iran will have anything new to offer at Thursday's meeting or how the outcome will affect U.S. policy toward the country. The continued standoff and suspicion surrounding Iran's weapons capabilities has embarrassed the European trio, frustrated Washington and worried international nuclear inspectors.
The diplomats -- all familiar with Iran's nuclear dossier -- cautioned against equating Tehran's move with the removal of atomic energy agency seals on nuclear equipment by North Korea two years ago as it expelled agency inspectors and declared itself no longer bound by the Nuclear Nonproliferation Treaty.
Unlike in North Korea, the seals on Iran's equipment "were not a legal requirement," one diplomat said. Tehran notified the atomic energy agency of its decision to break the seals, the diplomat said.
Iran continues to respect its pledge not to resume nuclear enrichment, said the diplomat.
Still, the move reflected Iranian defiance of international constraints on the country's nuclear program.
For the past year, the atomic energy agency has been carrying out stringent inspections of Iranian facilities, raising evidence that strengthened suspicions about Tehran's nuclear ambitions. In June, the atomic energy agency's board of governors rebuked Tehran in a sharply phrased resolution indicating it felt too many unanswered questions remained.
European diplomats said they are committed to finding a diplomatic way out of the stalemate.
"We're just going to sit with them and find out where we can go from here," said one European diplomat who agreed, on the condition of anonymity, to discuss strategy before the meeting.