The UN's nuclear watchdog on Thursday urged Iran to fully cooperate with it to resolve outstanding issues, Anadolu Agency reports.
Cornel Feruta, acting director general of International Atomic Energy Agency (IAEA), spoke to the board of governors at its headquarters in Vienna.
Feruta shared a report at the meeting which provided details of Iran's installation of a number of advanced types of centrifuge at the Pilot Fuel Enrichment Plant in Natanz, not only for research and development purposes but also to accumulate enriched uranium, and the resumption of uranium enrichment at Fordow plant.
"As I reported to the Board on November 7th, the agency has detected natural uranium particles of anthropogenic origin at a location in Iran not declared to the agency," Feruta said, according to a statement.
He said in their interactions with Iran since they have not received any additional information.
"It is essential that Iran works with the agency to resolve this matter promptly," he said.
Feruta said that a meeting between the agency and Iran is scheduled next week to discuss the matter.
Iran started to cut its commitments under the 2015 nuclear deal in a retaliatory move following the US decision to unilaterally withdraw from the agreement between Tehran and the five permanent members of the UN Security Council plus Germany and the European Union.
The US has since embarked on a diplomatic and economic campaign to ramp up pressure on Iran to force it to renegotiate the agreement.
The deal allows Iran to reduce its commitments in case of other parties' breaches. Tehran says the EU must be more active in implementing its part of the obligations, saying it will return to full compliance with the deal once the EU has nullified the US sanctions.
Feruta also called upon North Korea to comply fully with its obligations under United Nations Security Council resolutions, to cooperate promptly with the Agency, and to resolve all outstanding issues, including those that have arisen during the absence of agency inspectors from the country since 2009.
He renewed his call to Syria to cooperate fully with the IAEA in connection with unresolved issues.