South Korea's Joint Chiefs of Staff said it detected the launch but gave no details, saying an analysis is under way.

Japan confirmed a launch, with its Coast Guard quoting the Defence Ministry as saying "a possible ballistic missile was launched from North Korea."

The missile or missiles appear to have already fallen, the Coast Guard statement added.

This launch came amid increased cross border tension as the reclusive communist state has been sending balloons carrying garbage into South Korea.

North Korea's last missile launch prior to this one came on May 30, when Seoul accused Pyongyang of firing a volley of around 10 short-range ballistic missiles.

One day later North Korean state media released images of leader Kim Jong Un supervising tests of a multiple rocket launcher system.

Analysts have suggested the nuclear-armed North could be testing and ramping up production of artillery and cruise missiles before sending them to Russia for use in Ukraine.

In a report last month the Pentagon said it had confirmed this behavior.