The US Marines on Monday resumed flights of their controversial Osprey aircraft in Japan, less than a week after a crash off the southern island of Okinawa sparked local protests.

Last Tuesday an MV-22 Osprey made what Marines called a "controlled landing" just off the Okinawan coast during a night training flight that left the aircraft in pieces.

No one was killed but the accident sparked anger on the island -- a strategic outpost of US military power. In response, the Marines suspended flights of the tiltrotor aircraft in Japan pending an investigation.

The MV-22 Osprey can carry 24 troops and is half helicopter half turboprop, boasting the manoeuvrability of a chopper and the speed and range of a fixed-wing aircraft.

But a series of deadly accidents, mostly in the United States, has prompted frequent protests in Okinawa against the deployment of the aircraft.

The latest crash happened after the aircraft damaged one of its propellers during an aerial refuelling drill with another plane, according to the Marines.

US Forces Japan commander Lieutenant General Jerry Martinez said "a thorough, careful and exhaustive review" was conducted and explanation given to the Japanese government.

"While the investigation is ongoing, we are highly confident in our assessment that the cause of the mishap was due solely to the aircraft's rotor blades coming into contact with the refuelling line," he said in a statement.

Japanese television footage showed an Osprey taking off at the US Futenma airbase on Okinawa while the Marines confirmed flight operations had resumed.

Okinawa governor Takeshi Onaga, an outspoken critic of the US military presence, called the flight resumption "outrageous", though the central government expressed understanding.

"The US briefing (to the Japanese side) is reasonable... It is understandable that flights resume except for mid-air refuelling" which caused the accident, top government spokesman Yoshihide Suga told reporters.

More than half the approximately 47,000 US troops in Japan under a decades-long security alliance are stationed on Okinawa, the site of a major World War II battle that was followed by a 27-year US occupation of the island.

A series of crimes including rapes, assaults and hit-and-run accidents by US military personnel, their dependants and civilians have long sparked protests by Okinawa residents.