"The DPRK’s [Democratic People's Republic of Korea] nuclear activities remain a cause for serious concern. The continuation of the country’s nuclear programme is a clear violation of relevant UN Security Council resolutions and is deeply regrettable," the statement said.

According to the IAEA chief, there are indications consistent with the production of enriched uranium at a centrifuge enrichment facility at the Yongbyon nuclear site. Grossi added that North Korea was likely to continue internal construction activities at the experimental Light Water Reactor.

"I call upon the DPRK to comply fully with its obligations under Security Council resolutions, to cooperate promptly with the Agency in the full and effective implementation of its NPT Safeguards Agreement and to resolve all outstanding issues, especially those that have arisen during the absence of Agency inspectors from the country," the agency's head said.

North Korea ceased cooperation with the agency in 2009. IAEA has since repeatedly expressed readiness to take it back should Pyongyang agree and monitor its nuclear activities via open-source data and satellite imagery.

North Korea's nuclear program has been subject to concerns of the international community for decades now.

The United States and North Korea had two denuclearization summits in 2018 and 2019, but they eventually faced a deadlock as Washington demanded that Pyongyang completely dismantle all of its nuclear facilities in order to be given sanctions relief, while North Korea insisted on that part of the restrictions be lifted before denuclearization begins.