North Korean leader Kim Jong Un made good on his promise to demolish his country's nuclear test site, which was formally closed in a series of huge explosions on Thursday as a small group of foreign journalists watched.

The explosions at the test site deep in the mountains of the North's sparsely populated northeast were supposed to build confidence ahead of a planned summit next month between Kim and President Donald Trump.

But Trump canceled the meeting on Thursday, citing "tremendous anger and open hostility" in a North Korean statement released earlier in the day.

The blasts were centred on three tunnels at the underground site and a number of buildings in the surrounding area.

North Korea held a closing ceremony afterward with officials from its nuclear arms programme in attendance.

A group of journalists witnessed the demolition, which touched off landslides near the tunnel entrances and sent up clouds of smoke and dust.

North Korea's state media called the closure of the site part of a process to build "a nuclear-free, peaceful world" and "global nuclear disarmament".