Three American prisoners released from North Korea were on their way back to the US on Wednesday, in a further sign that Pyongyang was keen to improve relations ahead of a planned summit between its leader Kim Jong Un and President Donald Trump.

Pyongyang’s decision to release the three US citizens was the latest in a series of unprompted concessions that pave the way for the first meeting between a US president and a North Korean leader. That summit is expected to take place in the coming weeks.

The US has spent months conducting a global campaign aimed at forcing North Korea to abandon its atomic weapons programme. Late last month Pyongyang pledged to begin talks on denuclearisation. However, sceptics fear North Korea will use any talks to extract concessions on sanctions while continuing to develop its weapons capabilities in secret.