After scouring the waters off the Japanese coast following the crash of the US Osprey military aircraft during training exercises, rescue teams have reported seven missing US soldiers. 

The Japanese Defense Minister requested that US forces stationed in the country suspend all Osprey flights in the wake of the deadly incident except for search and rescue operations. 

"After receiving the first news, we searched to save lives, and this morning we made the request to the USFJ's commander," he said. 

The Japanese coastguard had announced earlier that one soldier was confirmed to have been killed. 

"One person was found and ... was confirmed dead in hospital," the coastguard said, adding that six people were aboard the aircraft at the time of the crash, revising down a previous estimate of eight.

The number of crew members was later revised again to eight confirming the initial reports.

"The cause of the mishap is currently unknown," US Air Force Special Operations Command said in a statement Wednesday, with emergency personnel "on scene conducting search and rescue operations."

Local emergency management officials reported that the aircraft had been "spewing fire from a left engine" before the crash.  

Read more: US Army temporarily grounds pilots after deadly crashes

Japanese broadcaster NHK reported that the Osprey left the Iwakuni US base in the Yamaguchi region and headed for the Kadena base in Okinawa.

The broadcaster also cited Defense Ministry sources as saying that the aircraft was a CV-22 Osprey belonging to the US Yokota air base in Tokyo.

The military drills, which involved military from the United States, Australia, Indonesia, the Philippines, and Timor-Leste, were suspended due to the crash.

Defective history

The Osprey aircraft, developed by Bell Helicopters and Boeing, is known for its defective history. Back in August, an MV-22B Osprey crash in Australia killed three US marines from the 23 that were on board during a military exercise for locally stationed troops.

Last year, four US Marines were killed in Norway when their MV-22B Osprey jet crashed during NATO training exercises.

In 2017, three Marines were killed when their Osprey crashed after clipping the back of a transport ship trying to land off Australia's north coast. And back in 2000, 19 Marines were killed when their Osprey jet crashed during drills in the state of Arizona.

Read more: Two killed in US National Guard helicopter crash in Alabama