VIENNA (AP) — The head of the U.N.'s atomic watchdog is calling on North Korea to allow inspectors back in to monitor its nuclear program.

Director General Yukiya Amano told the International Atomic Energy Agency on Thursday that Pyongyang had in September talked about denuclearization measures including the "permanent dismantlement of the nuclear facilities in Yongbyon" — a reactor where it produces plutonium.

Amano says there has been activity observed at Yongbyon, but "without access the agency cannot confirm the nature and purpose of these activities."

He called on North Korea to comply with U.N. Security Council resolutions and cooperate with the IAEA, whose inspectors were expelled in 2009.

He says the IAEA is continuing preparations to verify North Korea's nuclear program "if a political agreement is reached among countries concerned."