VIENNA (AP) - Iran moved closer to being able to produce nuclear warheads Monday with formal notification that it will enrich uranium to higher levels, even while insisting that the move was meant only to provide fuel for its research reactor.
Iranian envoy Ali Asghar Soltanieh told The Associated Press that he informed the International Atomic Energy Agency of the decision to enrich at least some of its low-enriched uranium stockpile to 20 percent, considered the threshold value for highly enriched uranium.
Soltanieh, who represents Iran at the Vienna-based IAEA, also said that the U.N. agency's inspectors now overseeing enrichment to low levels would be able to stay on site to fully monitor the process. And he blamed world powers for Iran's decision, asserting that it was their fault that a plan that foresaw Russian and French involvement in supplying the research reactor had failed.
"Until now, we have not received any response to our positive logical and technical proposal," he said. "We cannot leave hospitals and patients desperately waiting for radio isotopes" being produced at the Tehran reactor and used in cancer treatment, he added.
Iranian President Mahmoud Ahmadinejad had already announced Sunday that his country would significantly enrich at least some of the country's stockpile of uranium. Still, Monday's notification to the IAEA was important as formal confirmation of the plan, particularly because of the rash of conflicting signals sent in recent months by Iranian officials on the issue.
Although material for the fissile core of a nuclear warhead must be enriched to a level of 90 percent or more, just getting its stockpile to the 20 percent mark would be a major step for the country's nuclear program. While enriching to 20 percent would take about one year, using up to 2,000 centrifuges at Tehran's underground Natanz facility, any next step - moving from 20 to 90 percent - would take only half a year and between 500-1,000 centrifuges.
Achieving the 20-percent level "would be going most of the rest of the way to weapon-grade uranium," said David Albright, whose Washington-based Institute for Science and International Security tracks suspected proliferators.
Soltanieh declined to say how much of Iran's stockpile - now estimated at 1.8 tons - would be enriched. Nor did he say when the process would begin. On Sunday, Iranian officials said higher enrichment would start on Tuesday, but any reconfiguring of the centrifuge chains now enriching low enriched uranium is expected to take days, if not weeks.
The Iranian move came just days after Ahmadinejad appeared to move close to endorsing the original deal, which foresaw Tehran exporting the bulk of its low-enriched uranium to Russia for further enrichment and then conversion for fuel rods for the research reactor.
The original plan was welcomed internationally because it would have delayed Iran's ability to make a nuclear weapons by shipping out about 70 percent of its low-enriched uranium stockpile, thereby leaving it with not enough to make a bomb. Tehran denies nuclear weapons ambitions, insisting it needs to enrich to create fuel for an envisaged nuclear reactor network.
The plan was endorsed by the U.S., Russia, China, Britain, France and Germany - the six powers that originally elicited a tentative approval from Iran in landmark talks last fall. Since then, however, mixed messages from Tehran have infuriated the U.S. and its European allies, who claim Iran is only stalling for time as it attempts to build a nuclear weapon.
Even before Iran's formal notification of the IAEA, some of those nations criticized the plan and suggested it would be met by increased pressure for new penalties on the Islamic Republic.
Iran has defied five U.N. Security Council resolutions - and three sets of U.N. sanctions - aimed at pressuring it to freeze enrichment, and has instead steadily expanded its program.
Iran's enrichment plans "would be a deliberate breach" of the resolutions, the British Foreign Office said. In Berlin, Ulrich Wilhelm, the spokesman for German Chancellor Angela Merkel, said Germany and its allies were watching developments and were prepared to "continue along the path of raising diplomatic pressure."
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Associated Press writers Danica Kirka in London and Geir Moulson in Berlin contributed to this report.