Iran has suspended commitments under the 2015 international nuclear deal, a year after it was abandoned by the US.
President Hassan Rouhani said he would keep enriched uranium stocks in the country rather than sell them abroad.
He also threatened to resume production of more-highly-enriched uranium in 60 days if other signatories did not act to protect Iran from US sanctions.
The 2015 accord was aimed at curbing Iran’s nuclear ambitions in return for relief from sanctions.
Iran informed the remaining parties to the deal – France, Germany, Russia, China and the UK – of its decision on Wednesday morning.