One person was dead and seven missing after two Japanese military helicopters crashed after possibly colliding while out to sea, officials said.

A spokesperson for Japan’s self-defence force said the crash took place late on Saturday and one person was recovered and later confirmed dead.

The defence minister, Minoru Kihara, said rescuers “spotted what are believed to be part of the aircraft in the sea, and we believe that the two helicopters crashed”.

“At this point the cause is unknown, but firstly we do our best to save lives.”

He said the helicopters were “doing drills to counter submarines at night”.

Hours later, Kihara told reporters that the crew member who was rescued was confirmed dead.

He said the ministry retrieved flight recorders and was “analysing [the cause of the incident] including possibility of a collision between the two”.

The helicopters appeared to have crashed during night-time training off the Izu islands in the Pacific, broadcaster NHK reported.

Communication with one chopper was lost at 10.38pm off the island of Torishima, and one minute later an emergency signal was received from this aircraft, NHK reported.

About 25 minutes later, the military realised that communication with the other aircraft was lost in the same area.

The Mitsubishi SH-60K helicopters mainly operate from naval destroyers.

The navy said as there were no other aircraft nor vessels in nearby waters, involvement of another country in the incident was unlikely.

Japan is boosting defence spending and deepening cooperation with the US and other countries in Asia in response to growing Chinese assertiveness in the region and an unpredictable North Korea.

In April 2023 a Japanese army helicopter with 10 people on board crashed off Miyako island in southern Okinawa. There were no survivors.