Inspectors have found radioactive traces at an Iranian underground bunker, the U.N. atomic agency said Friday, a finding that could mean Iran has moved closer to reaching the uranium threshold needed to arm nuclear missiles.
The International Atomic Energy Agency said in a report obtained by the Associated Press that it was asking Tehran for an explanation. But the report was careful to avoid any suggestion that Iran was intentionally increasing the level of its uranium enrichment, noting that Tehran said a technical glitch was responsible.
Analysts as well as diplomats who had told the AP of the existence of the traces before publication of the confidential report also said the higher-enriched material could have been a mishap involving centrifuges over-performing as technicians adjusted their output rather than a dangerous step toward building a bomb.
Still, the finding was bound to resonate among the 35 IAEA board members for whom the report was prepared, among them the six world powers whose leaders had just concluded talks with Iran on its enrichment activities. The negotiations in Baghdad left the two sides still far apart over how to oversee Tehran's atomic program but resolved to keep dialogue going next month in Moscow as an alternative to possible military action.
The U.S. and the five other world powers are already concerned about Iran's output of uranium at the 20 percent level because material that high can be turned into weapons-grade much more quickly than its main, low-enriched stockpile.
The higher the enrichment, the easier it becomes to re-enrich uranium to warhead quality at 90 percent. As a result, the finding of traces at 27 percent at the Fordo enrichment plant in central Iran sparked international interest.
The report also expressed fears that a massive cleanup was under way at buildings at the Parchin military complex southeast of Tehran. The site is suspected of housing a pressure chamber and related equipment used to test ways of detonating a nuclear charge.
"Based on satellite imagery at this location the buildings of interest to the agency are now subject to extensive activities that could hamper the agency's ability to undertake effective verification" at the site, the report said.
Separately, a senior international official familiar with the issue said satellite photos showed trucks at the site and streams of liquid suggesting the interiors were being hosed down to wash away evidence of possible nuclear-related work.
The report said that over the past five months, the agency had "obtained more information" buttressing its suspicions about the Parchin site, which it has asked repeatedly to visit, only to be turned down by Iran.
Iran denies any plans to possess nuclear weapons but has for years declined offers of reactor fuel from abroad, including more recent inducements of 20-percent material if it stops producing at that level. The Islamic Republic says it wants to continue producing 20 percent uranium to fuel its research reactor and for medical purposes.
But its refusal to accept foreign offers has increased fears it may want to turn its enrichment activities toward producing nuclear arms.