Samples taken by the United Nations nuclear watchdog at a facility in Tehran showed traces of uranium that Iran has yet to explain, two unnamed diplomats told Reuters news agency, although they could not say whether the materials predated the 2015 nuclear deal, or were more recent, Al Jazeera reports.
The report published on Sunday said one of the diplomatic sources, however, acknowledged that the uranium traces were not highly enriched, meaning they were not purified to a level anywhere close to that needed for weapons.
The news comes as Iranian Foreign Minister Javad Zarif called on Cornel Feruta, acting chief of the International Atomic Energy Agency and his inspectors “to observe the principles of professional work, maintain confidentiality of activities, and keep doing its duties impartially”.
The IAEA is investigating the particles’ origin and has asked Iran for an explanation.
Tehran has not yet responded to the IAEA’s specific request for answers, according to the diplomats interviewed by Reuters, stoking more tensions between Washington and Tehran. Reuters did not identify the nationalities of the two diplomats.
Reuters first reported in April that the IAEA, which is policing the nuclear deal, had inspected the site – a step it had said it takes “only when necessary” – and environmental samples were taken there were sent for analysis.
United States and Israeli media have since reported that the samples turned up traces of radioactive material or matter.
Those traces were of uranium, the diplomats said – the same element Iran is enriching and one of only two fissile elements that can make the core of a nuclear bomb.
But since Iran has not yet given any to the IAEA it is hard to verify the particles’ origin, and it is also not clear whether the traces are remnants of material or activities that predate the landmark 2015 deal or more recent, the diplomats say.
“There are lots of possible explanations,” that diplomat told Reuters.