The country also agreed to hold no more than 300kg (660lbs) of low-enriched uranium.
Highly enriched uranium, which has a purity of 20% or more, is typically used in research reactors.
Under the deal, Iran capped its nuclear activities in return for a lifting of sanctions.
Donald Trump reimposed US sanctions in November 2018, and since July 2019 Iran has increasingly breached the pact’s restrictions.
In addition to operating advanced IR-6 centrifuges at its Fordo facility and enriching uranium up to 20% purity, the country has also started to produce smaller quantities of 60%-enriched uranium.
UPDATES TO FOLLOW…