Vienna International Centre, where IAEA offices are located
Vienna International Centre, where IAEA offices are locatediStock

Iran has rapidly installed extra uranium-enriching centrifuges at its Fordow site and begun setting up others, a new UN nuclear watchdog report found on Thursday, according to Reuters.

The confidential International Atomic Energy Agency (IAEA) report sent to member states described the steps Iran has taken so far, with the only concrete steps so far at either of its underground sites having been taken at Fordow, which is dug into a mountain.

"On 9 and 10 June ... Iran informed the Agency that eight cascades each containing 174 IR-6 centrifuges would be installed over the next 3-4 weeks in Unit 1 of FFEP (Fordow Fuel Enrichment Plant)," the IAEA report, which was seen by Reuters, said.

"On 11 June 2024, the Agency verified at FFEP that Iran had completed the installation of IR-6 centrifuges in two cascades in Unit 1. Installation of IR-6 centrifuges in four additional cascades was ongoing," the report said, referring to one of one of Iran's most advanced centrifuge models.

While Iran had long planned to install eight cascades of centrifuges at Fordow's Unit 1 it had only prepared the "necessary infrastructure" for the cascades rather than installing the machines themselves. Before these new cascades Fordow had eight operating in total.

Responding to the report, the US State Department said that Washington and its allies were prepared to continue to increase pressure on Iran if Tehran does not cooperate with the IAEA.

The report came days after the IAEA board passed a resolution censuring Iran over its lack of cooperation with the IAEA. Diplomats said Iran’s latest activity was as limited retaliation to the resolution.

The IAEA has long sought answers from Iran on uranium traces which were found at undeclared sites. While the number of sites under investigation has been narrowed to two from three, Iran still has yet to give the IAEA satisfactory answers on how the traces got there.

The IAEA released a report at the end of May which found that Iran has further increased its stockpile of uranium enriched to near weapons-grade levels.

The report said that as of May 11, Iran has 142.1 kilograms of uranium enriched up to 60% — an increase of 20.6 kilograms since the last report by the UN watchdog in February. Uranium enriched at 60% purity is just a short, technical step away from weapons-grade levels of 90%.

Previously, the IAEA found that, between June and November last year, Iran slowed down the enrichment to 3 kg per month, but that jumped back up to a rate of 9 kg at the end of the year.

The increase came soon after Tehran barred a third of the IAEA's core inspections team, including the most experienced, from taking part in agreed monitoring of the enrichment process.

That move was part of Iran’s scaling back of its compliance with the 2015 nuclear deal it signed with world powers, in response to then-US President Donald Trump’s withdrawal from the deal in 2018.