Japan ordered its military Saturday to prepare to shoot down a North Korean ballistic missile after Pyongyang said this week it was ready to launch its first military spy satellite.

Placing the satellite into orbit would require a long-range projectile, which North Korea is banned from launching because the United Nations views such exercises as tests of ballistic missile technology.

On Saturday Japanese minister Yasukazu Hamada told the country's Self-Defense Forces "there is a possibility of ordering destructive measures against ballistic missiles and others", according to a statement from the ministry of defence.

Hamada instructed troops to "implement measures necessary to limit damage in the event of a ballistic missile falling".

He ordered preparations for the deployment of destroyers equipped with SM-3 missile interceptors, as well as military units in the southern prefecture of Okinawa that can operate Patriot PAC-3 missiles.

In 2012 and 2016, North Korea tested ballistic missiles that Pyongyang called satellite launches.

Both missiles flew over the Okinawa region.

Japanese media reported Saturday that the defence ministry issued the same preparation orders in 2012.

Pyongyang has not provided a launch date, with leader Kim Jong Un only saying the satellite will be sent up "at the planned date".

On Tuesday G7 foreign ministers meeting in Japan demanded North Korea refrain from any further ballistic missile tests following a spate of launches this year.

The group of rich nations also warned Pyongyang against carrying out an expected nuclear weapons test and said there would be a "robust" response if it did not comply.

A week ago Pyongyang said it had successfully tested a solid-fuel intercontinental ballistic missile, hailing it as a breakthrough for the country's nuclear counterattack capabilities.