"I... hope that ways can be found to reduce current tensions through dialogue," International Atomic Energy Agency director general Yukiya Amano said in a speech opening the agency's quarterly board of governors meeting.

On May 8 Iran announced it no longer considered itself bound to keep to the limits of stocks of heavy water and enriched uranium. The limits were agreed as part of the 2015 Joint Comprehensive Plan of Action (JCPOA).

Tehran's move came a year after US President Donald Trump pulled out of the deal. Washington has also reinforced economic sanctions against the Islamic republic.

Iran has also said that if the other parties to the JCPOA did not speed up work on mitigating the effects of US sanctions, by early July it would stop abiding by restrictions on the level to which it can enrich uranium and on modifications to its Arak heavy water reactor.

Two weeks ago, the latest inspections report by the IAEA said that while stocks of uranium and heavy water had increased, they were as yet still within the limits set by the JCPOA.

"As I have constantly emphasised, the nuclear-related commitments entered into by Iran under the JCPOA represent a significant gain for nuclear verification," Amano said in his speech.

"It is essential that Iran fully implements its nuclear-related commitments under the JCPOA," he added.