8 November 2011
Last updated at 14:10 ET
Russia helped Iran build its Bushehr nuclear power plant
The UN's nuclear watchdog says it has information indicating Iran has carried out tests "relevant to the development of a nuclear explosive device".
In its latest report on Iran, the IAEA says the research includes computer models that could only be used to develop a nuclear bomb trigger.
Correspondents say this is the International Atomic Energy Agency's toughest report on Iran to date.
Iran says its nuclear programme is solely to generate civilian power.
The BBC's Bethany Bell, in Vienna, has examined the IAEA's latest quarterly report on Iran's nuclear programme.
She says the report gives detailed information - some of it new - suggesting that Iran conducted computer modelling of a kind that would only be relevant to a nuclear weapon.
The report, published on the Institute for Science and International Security website, notes that some of this research, conducted in 2008-09, is of "particular concern", our correspondent says.
"The application of such studies to anything other than a nuclear explosive is unclear to the agency," the report says.
- "Efforts, some successful, to procure nuclear related and dual-use equipment and material by military individuals and entities."
- "The acquisition of nuclear weapons development information and documentation from a clandestine nuclear supply network."
- "Efforts to develop undeclared pathways for the production of nuclear material."
- "Work on the development of an indigenous design of a nuclear weapon including the testing of components."
The report stops short, our correspondent adds, of saying explicitly that Iran is developing a nuclear bomb.
It says the information is "credible", and comes from some of the IAEA's 35 member states, from its own research and from Iran itself.
The report urges Iran "to engage substantively with the agency without delay for the purpose of providing clarifications."
Ahead of the report's release, there had been speculation in Israeli media about potential strikes on Iranian nuclear facilities.
Russia said the IAEA report had caused rising tension and more time was needed to determine whether it contained new, reliable evidence of a military element to Iran's nuclear programme.
Experts say Iran is at least one year away, perhaps several, from being able to produce a nuclear bomb. Some believe Iran's leadership wants to be in a position to able to produce such a weapon on short notice.
Iranian Foreign Minister Ali Akbar Salehi said there was "no serious proof" that Iran was going to create an atomic warhead.
"We have repeatedly stated that we are not going to create nuclear weapons," he said. "Our position has always been that we will never use our nuclear programme for purposes other than peaceful ones."
|Liveleak on Facebook|