Iran announced Sunday that it has begun enriching uranium up to 20% using technologically advanced centrifuges in its Fordow nuclear plant, according to state TV.

Behrouz Kamalvandi, a spokesman for Iran’s Atomic Energy Organization, said that for the first time, uranium enriched to 20% was collected from the IR-6 centrifuges on Saturday, and that Iran had briefed the UN nuclear watchdog about the development two weeks earlier. 

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Centrifuges are machines made for uranium enrichment to the highest degrees of purity. In 2015, when the nuclear deal was inked, world powers called on Fordow to become a research-and-development facility - but also restricted centrifuges to non-nuclear purposes.

Previously, Iran told the IAEA that it was preparing to enrich uranium through 166 advanced IR-6 centrifuges at the facility - but, the level at which the cascade would be enriching was not revealed.

The IAEA told the Associated Press that it verified on Saturday that Iran was using a set-up that allowed it to quickly and easily switch between enrichment levels.

Director General Rafael Grossi described the set-up as having "modified sub-headers." This allows the facility to inject gas enriched to 5% purity into a cascade of 166 IR-6 centrifuges to produce uranium enriched up to 20% purity.