IAEA confirms Iran temporarily stopped enriching uranium

Nuclear inspectors monitoring Iran found the country's enrichment program temporarily shut down a week ago, the International Atomic Energy Agency reported Tuesday, reflecting a possible setback for the cornerstone of the country's nuclear activities and source of national pride.

The UN nuclear monitor offered no reason for the Nov. 16 stoppage witnessed by IAEA staff and described in its latest report on Iran. The inspectors were on site at the Natanz enrichment plant in central Iran for only one or two hours, and it was unclear whether the shutdown lasted just hours, days, or longer. A senior diplomat familiar with the agency's overview of Teheran's atomic activities said the Iranians gave IAEA inspectors no time frame or explanation.

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The diplomat said he had known of only "two or three" such interruptions since monitoring of large scale enrichment Natanz began more than three years ago. In one case, he said, the Iranians had to change a tank containing the uranium gas fed into centrifuges — a procedure no longer necessary because cascades, or centrifuge configurations used to enrich, now had multiple tanks.

The diplomat — who asked for anonymity because the agency report is confidential — said, however, that technical problems were likely the reason for the most recent interruption.

Diplomats who first told The Associated Press of the interruption on Monday, also could not say what caused it. But some speculation focused on the Stuxnet worm, the computer virus thought to be aimed at Iran's nuclear program, which experts last week identified as being calibrated to destroy centrifuges by sending them spinning out of control. No one has claimed to be behind Stuxnet, but some analysts have speculated it originated in Israel.

Iran denied that Stuxnet had succeeded in damaging its nuclear program. The country's nuclear chief, Vice President Ali Akbar Salehi, on Tuesday accused the West of being behind a failed sabotage attempt and said details about the virus became known only after Iran's "enemies failed to achieve their goals."

Over the past several months, Iranian officials have acknowledged that the Stuxnet code had spread widely through Iranian industrial sites and infected several personal laptops belonging to employees at the country's first nuclear power plant.

The rare interruption in enrichment is significant against a backdrop of stagnation in the Iranian enrichment effort, appearing to be the latest evidence of serious difficulties in expanding the program after initial rapid growth.

Tehran has taken hundreds of centrifuges off line over the past 18 months, feeding speculation that enrichment was being hampered by major technical issues.

Iran's enrichment program is of international interest because the process can create both nuclear fuel and fissile nuclear warhead material. While Iran insists it wants to enrich only to run a nuclear reactor network, its nuclear secrecy, refusal to accept fuel from abroad and stonewalling of IAEA efforts to follow up on suspicions of covert experiments with components of a nuclear weapons program have heightened concerns — and led to UN sanctions.