A harshly worded new report by the U.N. atomic watchdog agency says that Iran was concealing some of its nuclear activities as recently as last month but that inspectors have found no proof of an active weapons program.
The International Atomic Energy Agency document says inspectors recently discovered that Iran had engaged in experiments to reprocess plutonium from spent nuclear fuel. Iran last month admitted the experiments on reprocessing, which could be a step toward weapons development.
The document also says that Iran now acknowledges operating a secret uranium enrichment program using lasers for 12 years and using uranium chemicals imported from China in experiments to enrich uranium at a previously secret location. Enrichment is a process that purifies uranium for use in reactors or weapons.
Earlier, when the IAEA had noted that the Chinese chemicals were missing and asked Iran about them, Tehran claimed they had leaked out of storage canisters.
A copy of the 30-page report was provided to the Los Angeles Times on Monday by a Western diplomat in Vienna, where the IAEA is headquartered.
In its toughest language, the report said: "Based on all information currently available to the agency, it is clear that Iran has failed in a number of instances over an extended period of time to meet its obligations under its safeguard agreement with respect to the reporting of nuclear material and its processing and use."
Mohamed ElBaradei, director-general of the IAEA, said in the report that inspectors had turned up no evidence that the concealed activities were linked to a nuclear weapons program.
"However, given Iran's past pattern of concealment, it will take some time before the agency is able to conclude that Iran's nuclear program is exclusively for peaceful purpose," he said.
The report, which notes that the IAEA investigation is continuing, detailed nine separate instances in which it said Iran had failed to report nuclear activities as required under the Nuclear Nonproliferation Treaty or failed to provide required information to the agency.
The Western diplomat in Vienna said in a telephone interview that this was the first time the agency had used the word "failed" in a report on Iran and that the language marked significant concerns on the part of the IAEA.
Still, the inconclusive verdict on weapons is likely to buy Iran more time to try to persuade the international community that it is pursuing nuclear power to generate electricity, not build an atomic bomb.
The U.S. has accused Iran of using its civilian nuclear power program as a front for attempts to develop atomic weapons. Washington has been pressuring the countries represented on the IAEA's Board of Governors to refer the issue to the U.N. Security Council for possible sanctions against Iran.
The IAEA board is scheduled to take up the issue at a meeting set to begin Nov. 20 in Vienna.
The board got tough with Tehran in September after IAEA inspectors discovered traces of uranium enriched to weapons-grade levels at two locations in Iran. Tehran had claimed that the traces were brought into Iran on contaminated machinery bought on the black market.
The board set an Oct. 31 deadline for Iran to agree to more intrusive inspections and halt its program to enrich uranium. Under international pressure, Iran agreed last month to accept the additional inspections and temporarily suspend its enrichment program. It also turned over a dossier on the history of its atomic program to the IAEA.
In Moscow on Monday, a senior Iranian official told Russian President Vladimir V. Putin that Tehran would provide the IAEA with a letter formally accepting the additional inspections this week and that it was immediately suspending its enrichment temporarily.
A diplomat in Vienna said the Moscow announcement was probably timed to soften the criticism contained in the IAEA report, which was distributed to board members Monday.
The most glaring criticisms in the report dealt with the discovery of the plutonium experiments, the existence of the secret laser enrichment program and the uranium enrichment tests using the Chinese material.
The plutonium reprocessing experiments were performed secretly at two facilities in Tehran between 1988 and 1992. Iran told the agency that the research was carried out to learn about the nuclear fuel cycle, but the steps also could be interpreted as part of a weapons program.
The report says the experiments had not been disclosed to the agency, as required, and that waste was dumped in a salt marsh.
In another incident, the report says Iran admitted in an Oct. 21 letter that it had used uranium hexafluoride imported from China to test equipment for its uranium enrichment program at the Kalaye Electric Co., a small complex northwest of Tehran that had been identified as a watch factory.
The tests were conducted from 1998 until 2002 on centrifuges, which are used in large numbers to purify uranium for use as reactor fuel or in weapons. After the tests, the centrifuges were moved to a huge underground complex under construction near Natanz in central Iran.
When inspectors first visited Kalaye last March, they were refused access. Later, Iran admitted that it had conducted enrichment experiments at Kalaye but claimed the tests were simulations and did not involve nuclear material.
By the time the inspectors were permitted to return to Kalaye in August, they found that walls had been removed and significant portions of the complex had been repainted. Some officials suspected it was an effort to conceal unreported activities there, but Iran said the changes were normal renovations.
Sophisticated environmental testing by the inspectors turned up trace amounts of uranium that had been enriched to a level usable in weapons. The new report said Iran admitted that its tests involved small amounts of uranium gas imported in 1991 from China. Traces also were discovered on centrifuges at the Natanz plant.
Iran continues to maintain that the centrifuges were contaminated with weapons-grade uranium when they were purchased on the black market.
The origin of the centrifuges is still unclear.