It is essential that Iran resolves issues over undeclared “uranium particles” which were detected at a site in the country, said the International Atomic Energy Agency (IAEA) on Thursday, Eurasia Diary reports citing Al-Arabiya

“The Agency has detected natural uranium particles of anthropogenic origin at a location in Iran not declared to the Agency,” explained the IAEA’s Acting Director General Cornel Feruta in remarks made to the board posted on their website.

“It is essential that Iran works with the Agency to resolve this matter promptly,” he said, adding that a meeting between the Agency and Iran to discuss the issue was scheduled for next week. Feruta did not reveal the location where the particles were found.

The European Union called on Iran to answer the IAEA’s concerns immediately, reported Al Arabiya's correspondent.

The IAEA is an autonomous organization that works as the UN’s nuclear watchdog.

Iran’s nuclear program has been the target of US sanctions after Washington pulled out of the 2015 nuclear deal, citing Iran's continued support for regional proxy organizations and destabilizing activities.

Iran has since breached the limits in the nuclear deal, most recently by accumulating slightly more than 130 tons of heavy water, a substance used in a type of reactor it is developing, according to an IAEA report on Monday.

“The right amount of uranium enrichment for the world’s largest state sponsor of terror is zero,” US Secretary of State Mike Pompeo said, announcing on Tuesday the end of sanctions waivers for Iran's Fordow site, where the IAEA says Tehran has been enriching uranium.