A view of the Natanz uranium enrichment facility 250 km (155 miles) south of the Iranian capital Tehran, March 30, 2005. Photo: REUTERS/Raheb Homavandi

Iran has started enriching uranium at its underground Natanz plant with a second type of advanced centrifuge, the IR-4, the UN nuclear watchdog said in a report obtained by Reuters on Tuesday, in a further breach of Tehran’s deal with major powers.

Last year Iran started moving three cascades, or clusters, of different advanced models from an above-ground plant at Natanz to the below-ground Fuel Enrichment Plant (FEP). It is already enriching underground with IR-2m centrifuges. The deal only lets it enrich there with first-generation IR-1 machines.

“On 15 March 2021, the Agency verified that Iran began feeding the cascade of 174 IR-4 centrifuges already installed at FEP with natural UF6,” the International Atomic Energy Agency said in a report to member states dated Monday, referring to uranium hexafluoride, the form in which uranium is fed into centrifuges for enrichment.