Iran has declared that it will no longer abide by any of the restrictions imposed by the 2015 nuclear deal.
In a statement it said it would no longer observe limitations on its capacity for enrichment, the level of enrichment, the stock of enriched material, or research and development.
The statement came after a meeting of the Iranian cabinet in Tehran.
It comes amid heightened tensions over the killing of Iranian General Qasem Soleimani by the US in Baghdad.
Under the 2015 accord, Iran agreed to limit its sensitive nuclear activities and allow in international inspectors in return for the lifting of crippling economic sanctions.
US President Donald Trump abandoned it in 2018, saying he wanted to force Iran to negotiate a new deal that would place indefinite curbs on its nuclear programme and also halt its development of ballistic missiles.
Iran refused and has since been gradually rolling back its commitments under the agreement.
Earlier on Sunday, Iraqi MPs passed a non-binding resolution calling for foreign troops to leave the country after the killing of Soleimani in a drone strike at Baghdad airport on Friday.
About 5,000 US soldiers are in Iraq as part of the international coalition against the Islamic State (IS) group.