Despite an announcement from Iran earlier this month that it no longer considered itself bound by the agreed restrictions on stocks of enriched uranium and heavy water, stocks of both did not exceed the ceilings set in the 2015 agreement, the report said.

As of May 26, Iran had 125.2 metric tonnes of heavy water, an increase of 0.4 tonnes on February but stil under the 130-tonne limit.

As of 20 May, Iran had 174.1 kg of enriched uranium, up from 163.8kg in February but again well within the relevant of limit 300kg.

Earlier this month Iran announced it was suspending some of its commitments under the 2015 Joint Comprehensive Plan of Action (JCPOA).

The move came a year after US President Donald Trump pulled out of the deal. His administration has also reinforced economic sanctions against the Islamic republic.