TOKYO (AFP) - A US military jet crashed off the southern Japanese island of Okinawa on Thursday (Sep 22) but the pilot was safely rescued, authorities said.

The wreckage of the plane was found 150km off Okinawa's main island in the mid-afternoon, according to the Japan Coast Guard.

"We received a rescue request from Kadena Air Base," a coast guard spokesman told AFP, adding they sent a patrol ship and plane.

But the US Marine Corps said in a press release that the pilot on the AV-8 Harrier jet ejected safely and was rescued by the US Air Force.

Officials would not confirm if anyone else was on the plane or if any injuries were reported.

"The cause of the incident is under investigation," the Marine Corps said.

Last year, seven crew members were injured after a US military helicopter crashed into the sea off Okinawa.

All 17 people aboard were rescued.

More than half the 47,000 American 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 military personnel, dependants and civilians have long sparked protests against a US airbase on the island.

Tokyo wants to move the unpopular Futenma airbase in a crowded residential district on Okinawa to a sparsely populated area in its north, but many locals want the base moved off the island altogether.

A Japanese court last week approved Tokyo's plan to relocate the base in a move unlikely to immediately resolve the long-running spat between central and local authorities.