The US Marine Corps may ground its entire air fleet for a safety review following the crash of an Osprey tilt-rotor aircraft in Australia that killed three Marines, a defense official said Monday.

The Japan-based Marine MV-22 Osprey crashed Saturday during an exercise off the Australian coast, leaving three service members missing and presumed dead.

"We are looking at our options in terms of reviewing safety across the Marine Corps fleet at the moment ... pending an across-the-board safety review," a US defense official told AFP, noting that the grounding could affect all flying squads in the service.

US officials are also weighing a request by Japan's new defense minister, who told the US military on Monday of his "many concerns" after it flew an Osprey in Japan following the crash.

Itsunori Onodera, appointed Thursday as Japan's defense minister, asked the US to temporarily stop flying the aircraft in his country following the accident.

"We have still many concerns," Onodera said during a meeting with Major General Charles Chiarotti, deputy commander of US Forces in Japan, according to a defense ministry spokesman.

Japanese media said the flight took place on the southern island of Okinawa, where a squadron of Ospreys is stationed at the US Marines' Futenma base.

Chiarotti told Onodera the flight was necessary for operational reasons and that its safety was confirmed, according to Japan's defense ministry.

Pentagon spokesman Captain Jeff Davis did not say whether the Marines would honor Tokyo's request but stressed that safety was a paramount concern.

"We always take the safety of all our operations, not just with MV-22s, very seriously and we recognize that we are guests of the government of Japan," Davis said.

"I would also say that these are forces ... that are there specifically for the defense of Japan and for furthering our shared security," he added.

- Trying to land -

The MV-22 -- a hybrid helicopter-turboprop with a checkered safety record -- has two engines positioned on fixed wingtips that allow it to land and take off vertically. It can travel much faster than a helicopter.

According to the US official, the Osprey crashed after clipping the back of the USS Green Bay while trying to land on the amphibious transport ship.

The Okinawa-based aircraft which crashed was in Australia as part of a joint military exercise called Talisman Sabre, which has just ended in Queensland state.

There have been a series of deadly incidents, mostly in the United States, involving the aircraft.

In April 2000, 19 Marines were killed in an MV-22 crash in Arizona.

Marines say the problems that plagued the aircraft while it was being developed have been fixed, and it is now actually one of the safest in the air fleet.

Locals on Okinawa have protested at the deployment of Ospreys to Futenma, which sits in the middle of a crowded city.

In December a "controlled landing" of an Osprey just off the Okinawan coast during a training flight sparked local anger. The aircraft broke into pieces but no one was killed.

Source: AFP