WASHINGTON — Iranian stonewalling has stalled a U.N. investigation into whether Iran conducted nuclear weapons research, according to a new U.N. nuclear watchdog report that for the first time raised the possibility that foreign experts may have assisted in Iranian nuclear experiments.
"We would describe it as gridlock," said a senior U.N. official, who discussed the report's findings Monday in return for anonymity because the six-page document was restricted to the 35-member board of the Vienna, Austria-based U.N. International Atomic Energy Agency.
The report, a copy of which was obtained by McClatchy, also found that Iran has made significant progress since May in running its industrial-scale uranium enrichment plant at Natanz, installing hundreds of new machines and boosting the average daily output of low-enriched uranium by more than 50 percent.
Low-enriched uranium is used to fuel power plants, the declared purpose of Iran's program. U.S. and European officials charge that Iran is perfecting the process in order to produce highly enriched uranium, a fuel used in the explosive cores of nuclear warheads.
The report prompted the United States and Britain to issue fresh warnings that the U.N. Security Council could tighten sanctions against Iran for persisting in defying demands to suspend its enrichment program.
It was unclear, however, if Russia, which has resisted tougher sanctions and remains at loggerheads with Western powers over its invasion of Georgia, would back a fourth round of punitive measures against the Islamic Republic.
Iran has defied four U.N. resolutions demanding that it suspend the uranium enrichment program that it hid from U.N. inspectors for 18 years. Tehran rejected an offer this summer from the United States and the European Union for political, technological and economic rewards in return for talks on implementing the demand.
President Bush insists that he wants to resolve the dispute diplomatically, but has refused to rule out military strikes against Iran's nuclear facilities.
The IAEA report expressed "serious concern" at Tehran's refusal to cooperate in an inquiry into materials the IAEA obtained from the U.S. and other governments. These outlined alleged studies of conventional high explosive triggers for nuclear weapons, uranium enrichment and modifications of missile nosecones to accommodate nuclear warheads.
The report disclosed that the IAEA recently received information indicating the possible "assistance of foreign expertise" in the alleged experiments pertaining to conventional high explosive triggers for implosion-type nuclear weapons.
The senior U.N. official declined to elaborate except to say that it does not appear that the expertise came from a government or the Pakistani-led network that supplied illicit nuclear materials to Iran, Libya and North Korea.
"We think it's serious enough to pursue this," said the U.N. official.
U.S. officials declined to discuss the issue. But non-proliferation experts in and out of the U.S. government have worried for years about the threat of nuclear weapons experts from the former Soviet bloc or elsewhere marketing their skills to regimes bent on developing nuclear weapons.
Many of the IAEA documents came from a laptop computer obtained by the CIA. But the IAEA says it has received materials from other governments that appear to corroborate the laptop's contents.
Iranian officials substantiated as "factually accurate" some information in the documents. But they dismissed the materials themselves as forgeries during meetings with IAEA officials last month in Tehran, the report said.
Iranian officials also failed to answer questions about technical activities and the procurement of nuclear components by military-related entities and their staffs, the report said.
"Iran needs to provide the agency with substantive information to support its statements and provide access to relevant documentation and individuals in this regard," it said.
The IAEA cannot certify the peaceful nature of Iran's program unless "Iran provides such transparency" and implements an agreement giving U.N. inspectors greater access to nuclear-related facilities, said the report.
A U.S. intelligence report released earlier this year said that Iran halted a nuclear weapons development program in mid-2003, but assessed that it had kept open the option of restarting it.
David Albright, an expert who monitors Iran's program, said the new report indicates that Iranian technicians have surmounted problems they were having installing and operating the more than 3,000 centrifuges, the machines used to enrich uranium, at the underground industrial-scale plant at Natanz.
"They are moving forward," said Albright, head of the Institute for Science in International Security, an independent policy research organization, adding that the machines are now running "at about 85 percent of their optimal output."
The report said that Iran has produced 480 kilograms of low-enriched uranium. Some 1,700 kilograms of low-enriched are needed to produce enough highly enriched uranium for a nuclear weapon.
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