The future of the international effort to eliminate North Korea’s nuclear weapons was in doubt on Tuesday night after Pyongyang said it would suspend efforts to disable its nuclear facilities and would consider putting its Yongbyon reactor back into action.

The announcement, which North Korea said was in response to Washington’s delay in removing it from the US list of state sponsors of terrorism, comes at a time of uncertainty about the so-called “six party” talks on Pyongyang’s nuclear programme, which involve US, China, Russia, Japan and the two Korean states.