Iran has declared 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.
Tensions have been high over the killing of Iranian General Qasem Soleimani by the US in Baghdad.
At least two rockets fell on Baghdad’s Green Zone, where the US embassy is located, on Sunday evening, as well as in another part of the city, where four people were reportedly injured.
Hundreds of thousands turned out in Iran on Sunday to give Soleimani a hero’s welcome ahead of his funeral on Tuesday.
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 had since been gradually rolling back its commitments under the agreement.
Iraqi MPs back call to expel US troops
Iraqi MPs have passed a non-binding resolution calling for foreign troops to leave, after the US killed Iranian general Qasem Soleimani in a drone strike at Baghdad airport last week.
Some 5,000 US soldiers are in Iraq as part of the international coalition against the Islamic State (IS) group.
The coalition paused operations against IS in Iraq just before Sunday’s vote.
In another development, Iran announced it was removing all limits on its enrichment of uranium.
The move further distanced Tehran from an agreement struck with the US and other world powers in 2015 aimed at preventing it developing nuclear weapons.
Soleimani’s killing marks a major escalation in tensions between Tehran and Washington, which pulled out of the nuclear agreement in 2018.