Iran has begun curbing uranium enrichment, state TV says, under a nuclear deal which will also trigger an easing of international sanctions.
Centrifuges used for enrichment were disconnected at the Nantaz plant, according to TV.
Diplomats and officials close to the UN nuclear watchdog, the IAEA, confirmed that the process had begun.
The move is part of a nuclear deal reached with the US, Russia, China and European powers last November.
Curbs on enrichment should pave the way for partial suspension of EU and US sanctions, allowing Iran to restart petrochemical exports and trade in gold, worth billions of dollars.
“The IAEA inspectors in the Natanz plant are disconnecting cascades,” the head of Iran’s Atomic Energy Organisation, Ali Akbar Salehi, said. “The sanctions iceberg against Iran is melting.”
The IAEA would not comment officially on the results of its inspection, but told the BBC that a report had been sent to the parties to the nuclear agreement.
An envoy to the UN agency told AFP news agency that Iran had started implementing its side of the deal: “It’s all fine, all their requirements have been fulfilled.” Reuters said it had obtained a leaked copy of the inspectors’ report.
The agreement is designed to prevent Teheran developing atomic weapons, though it denies trying to do so, saying its nuclear programme is solely for peaceful purposes.