Iran is expanding its enrichment of uranium beyond the highly enriched threshold of 20% purity at a Natanz plant where it is already enriching to 60%, the UN nuclear watchdog said on Monday.
However, the new activity does not involve keeping the product, said the International Atomic Energy Agency (IAEA) in a report seen by the Reuters news agency.
The move has prompted the IAEA to "increase the frequency and intensity of its safeguards activities" at the above-ground Pilot Fuel Enrichment Plant (PFEP) at Natanz, the agency said.
The IAEA said in a statement outlining the report that Iran informed it last week of changes to the setup of centrifuges, machines that enrich uranium, at the plant - Iran would feed uranium enriched to up to 20% into limited numbers of extra centrifuges without collecting the product.
"On 25 October 2021, the Agency verified that Iran began feeding (uranium hexafluoride gas) enriched up to 20% U-235 into a single IR-6 centrifuge in R&D line 2 at PFEP and that the resulting product and tails streams were being re-combined," the IAEA report said, meaning that after separating the enriched product it was mixed with the centrifuge's waste and not kept.
Iran had said it planned to also feed uranium enriched to up to 20% into other single centrifuges or small- to medium-sized cascades, or clusters, of machines on the same line, but those were not being fed at the time, the IAEA said.
Iran last April reported an explosion at the Natanz plant which disrupted the electrical distribution grid at the site. An Iranian official blamed "sabotage" for the of the Natanz nuclear facility.
Iran’s top nuclear official condemned the attack on the Natanz plant as an act of “nuclear terrorism”, and hinted that Iran may retaliate. Then-Iranian Foreign Minister Mohammad Javad Zarif blamed Israel for the incident and promised revenge.
The IAEA later said that Iran has installed extra advanced centrifuges at the underground uranium enrichment plant and plans to add even more.
In July, diplomats said Iran had been restricting UN nuclear inspectors’ access to its main uranium enrichment plant at Natanz, citing security concerns following the April attack on the site.