Iran appears to have worked on designing an atomic bomb and may still be conducting research relevant for such weapons, the UN nuclear watchdog said in its most detailed and hard-hitting report on military dimensions to Tehran's nuclear programme.
Citing what it called "credible" information from member states and elsewhere, the agency listed a series of activities applicable to developing nuclear weapons, such as high explosives testing and development of an atomic bomb trigger.
The hotly anticipated International Atomic Energy Agency (IAEA) report, preceded by Israeli media speculation of pre-emptive air strikes on Iranian nuclear sites, presented new evidence pointing to concerted efforts to obtain nuclear arms capability.
Some of the cited research and development activities by Iran have both civilian and military applications, but "others are specific to nuclear weapons," said the report, obtained by Reuters on Tuesday ahead of an IAEA board of governors meeting.
Tehran quickly rejected the report. "(It) is unbalanced, unprofessional and politically motivated," said Ali Asghar Soltanieh, Iran's ambassador to the IAEA.
The United States may impose more sanctions on Iran, possibly on commercial banks or front companies, but is unlikely to go after its oil and gas sector or its central bank for now, a US official said today.
"I think you will see bilateral sanctions increasing," the official, speaking on condition of anonymity.
US proliferation expert David Albright said: "I think the facts lay out a pretty overwhelming case that this was a pretty sophisticated nuclear weapons effort aimed at miniaturising a warhead for a ballistic missile."
"It's overwhelming in the amount of details, it is a pretty convincing case," he told Reuters from Washington.
Tehran has dismissed the allegations of covert atomic bomb research, based largely on Western intelligence funnelled to the IAEA, as fabricated and baseless.
The IAEA said it had carefully assessed the information passed on from member states and found it consistent in terms of technical content, individuals and organisations involved and time frames. It said it had gathered its own supportive details.
"The agency has serious concerns regarding possible military dimensions to Iran's nuclear programme," the IAEA said in the report, which included an unusual 13-page annex with technical descriptions of research with explosives and computer simulations applicable to nuclear detonations.
The Vienna-based agency said the data "indicates that Iran has carried out activities relevant to the development of a nuclear explosive device."
It added: "The information also indicates that prior to the end of 2003, these activities took place under a structured programme, and that some activities may still be ongoing."
US spy services estimated in 2007 that Iran had halted outright "weaponisation" research four years previously, but also that the Islamic Republic was continuing efforts to master technology usable in nuclear explosives.
The IAEA report included information from both before and after 2003.
It expressed "particular concern" about information provided by two member states that Iran had carried out computer modelling studies linked to nuclear weapons in 2008-09.
"The application of such studies to anything other than a nuclear explosive is unclear to the agency," the IAEA said.
The information also indicated that Iran had built a large explosives vessel at the Parchin military complex southeast of Tehran in which to conduct hydrodynamic experiments, which are "strong indicators of possible weapon development."
For several years the IAEA has been investigating Western intelligence reports indicating that Iran has coordinated efforts to process uranium, test high explosives and revamp a ballistic missile cone to accommodate a nuclear warhead.
Iran, the world's No. 5 oil exporter, insists that its programme to enrich uranium is for a future network of nuclear power stations to provide electricity for a rapidly growing population, so that it can export more of its oil and gas.
But Tehran's history of hiding sensitive nuclear activity from the IAEA, continued restrictions on IAEA access and its refusal to suspend enrichment -
which can yield fuel for atom bombs - have drawn four rounds of U.N. sanctions, as well as separate punitive steps by the United States and European Union.
IAEA officials have often complained that Iran has refused, for at least three years, to seriously answer the agency's questions about accusations of illicit nuclear activity.
Reuters