
The International Atomic Energy Agency (IAEA) in a report said Iran's enriched uranium stockpile is more than five times the limit fixed under the 2015 nuclear deal.
The atomic agency said as of February 19, Iran's uranium stockpile stood at1,510 kilogrammes, as compared to 300 kg limit set under the 2015 agreement by world powers.
The UN watchdog said it was denied entry to at least two sites in January by Iranian authorities.
The agency in its report said it had "identified a number of questions related to possible undeclared nuclear material and nuclear-related activities."
In November last year, the UN nuclear watchdog had urged Iran to explain the presence of uranium particles at an undeclared site.
Iran had rejected IAEA's report of traces of uranium found in unnamed sites.
Iran has openly breached several parts of the deal it signed with the US as well as Britain, China, France, Germany and Russia, in which it committed to scaling back its nuclear programme in exchange for sanctions relief.
The IAEA had earlier flagged Iran's stock of heavy water for reactors had crossed the 130-tonne limit.