The US has grounded its entire fleet of Osprey helicopters after a report said a crash off the coast of Japan last week, which killed eight crewmembers, was due to a malfunction, Paralel.Az reports citing BBC.

Air Force and Navy officials said they had taken the step "to mitigate risk while the investigation continues".

Not all of the remains of service members killed in the crash have been recovered yet.

Japan grounded its fleet of 14 Ospreys after the crash as well.

Japan is the only other nation known to operate Ospreys, which operate both as a helicopter and an aircraft with a propeller.

The Air Force said the American fleet is expected to remain grounded until it completes its investigation. It did not say how long that might take.

At the time of the crash, the Osprey had been on a training flight from a US Marine Corps air base in Yamaguchi Prefecture and was headed towards Kadena Air Base in Okinawa.

Eyewitnesses said the aircraft flipped over and was on fire before crashing offshore.

First introduced in 2007 after decades of testing, Ospreys have come under scrutiny for being involved in multiple fatal accidents since its time in service.

In August, a different model Osprey crashed during a military exercise in Australia, killing three US Marines and injuring 20 others.

Another crash involving an Osprey in the California desert last year caused the deaths of five Marines.