A steady expansion of Iran's nuclear program was interrupted at least briefly this month by the complete shutdown of its uranium enrichment production, according to an analysis of a report Tuesday by the United Nations' nuclear watchdog.
Despite international sanctions and reports in the Western media that a computer virus had damaged sensitive equipment, Iran ramped up its production rate of enriched uranium and apparently worked out technical glitches to increase the number of delicate centrifuges producing the nuclear fuel, the latest quarterly report by the International Atomic Energy Agency indicates.
But during a Nov. 16 visit, a cryptic footnote in the report says, inspectors observed that no uranium was being fed into any centrifuges, though Iranians claimed Monday that they were operating again within days. Some observers have speculated that a virus called Stuxnet may have caused the shutdown, claims rejected as "lies" on Tuesday by Ali Akbar Salehi, the head of Iran's nuclear program.
But in comments to state media, he failed to offer an explanation for the stoppage.
The quarterly report, delivered to the agency's board of governors, offers a snapshot of a nuclear program that the United States and its allies have vowed to curb. They suspect Iran is seeking to build atomic weapons in violation of its treaty obligations. Tehran vehemently denies the charge, saying it is enriching uranium for peaceful uses.
Diplomats expect that Iranian officials will meet next month with their American, European, Russian and Chinese counterparts in an effort to restart dormant negotiations to resolve the years-long impasse. But no date, venue or agenda has been confirmed.
Iran has continued construction on nuclear facilities and mining for raw uranium as well as the production of the nuclear fuel that has alarmed Western and Israeli leaders.
The Islamic Republic had accumulated about 7,000 pounds of low-enriched uranium by this month, according to the report, theoretically enough to build nearly three nuclear weapons if the material was further purified to much higher levels. Tehran has slightly increased its rate of production to nearly 290 pounds a month, compared with a previous monthly rate of no more than 265 pounds.
From a cursory look it did not appear that this month's interruption affected Iran's total enriched uranium claims, said David Albright of the Institute for Science and International Security, an arms-control think tank. "The lasting damage didn't seem to be that great. Production went up slightly."
Iran has also produced 73 pounds of uranium enriched to 20%, which it says is needed for a Tehran medical reactor. Salehi said Tuesday that Iran plans to begin fueling that reactor in about a year.
During a Nov. 5 inspection, Iran was feeding enriched uranium into at least 4,756 of its nearly 9,000 centrifuges, almost 1,000 more than during an Aug. 28 inspection and the highest number since May 2009, when the number of devices operating began to fall. The dramatic increase suggests that Iran had ironed out technical glitches that had for months kept more than half its centrifuges idle, but it may not take into account any damage that might have occurred later in November.
Special correspondent Julia Damianova in Istanbul, Turkey, contributed to this report.