The shutdown of North Korea’s main nuclear reactor should be a “smooth process” that will be completed within a month, provided that Pyongyang acts in a “transparent” manner, the head of the International Atomic Energy Agency said on Thursday.

With monitors from the United Nations nuclear watchdog due to return to Pyongyang on Saturday and multilateral disarmament talks set to resume in Beijing next week, the process of luring North Korean down the path to denuclearisation is gathering pace.