The earthquake, which appeared to have occurred naturally, struck 41 kilometres (25 miles) northwest of Kilju, which is home to the nuclear test site, according to the Korea Meteorological Administration.

The quake was detected at 7:00 pm (1000 GMT) at a depth of 20 kilometres (12 miles).

North Korea conducted six nuclear tests at the Punggye-ri nuclear test facility between 2006 and 2017.

The 2017 nuclear test triggered a 6.3-magnitude quake that was felt across the border in China.