Search operation under way after the SH-60 patrol helicopters possibly collided with each other during antisubmarine exercise off Izu Islands.

Two Japanese navy helicopters carrying eight crew members crashed into the Pacific Ocean during a night-time training exercise after possibly colliding with each other, killing one person, the defence minister said on Sunday.

Rescuers on Sunday searched for seven others who were still missing.

The two SH-60 patrol helicopters were conducting antisubmarine exercises on Saturday night near Torishima in the remote Izu island group, off the southern coast of central Japan.

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

He also said the ministry “discovered the flight recorders in places close to each other”, and so the “possibility is high that [the two helicopters] collided”.

“The flight recorders are being analysed,” Chief of Staff Ryo Sakai of the Japan Maritime Self-Defense Force (JMSDF) told reporters, as officials are interviewing the crew of a third helicopter that was joining the drill but was not involved in the accident.

Communication with one chopper was lost at 10:38pm (13:38 GMT) off the island of Torishima, and one minute later an emergency signal was received from this aircraft, broadcaster NHK reported.

Approximately 25 minutes later, at about 11:04pm, the military realised that communication with the other aircraft was also lost in the same area.

The Mitsubishi SH-60K helicopters from the JMSDF are mainly based on and operate from naval destroyers.

The JMSDF said as there were no other aircraft nor vessels in nearby waters, involvement of another country in the incident is unlikely, NHK added.

US Ambassador to Japan Rahm Emanuel said in a message on social platform X that the United States had offered to help with the search and rescue.

“We will stand together, side by side, with our friend and ally, Japan. My thoughts are with the crew members, and their families and friends during this challenging time,” he said.

The crash comes a year after a Ground Self-Defence Force UH-60 Blackhawk crashed off the southwestern Japanese island of Miyako, due to an engine output problem known as “rollback”, leaving all 10 crew members dead, which shocked the nation.

In 2017, a Japanese navy SH-60J, an earlier generation Seahawk, crashed during a night-time flight training off Aomori due to human error.