At least one person was killed on Wednesday when a US Osprey military aircraft crashed off the coast of Japan, the coastguard announced.

"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.

"We received information at 2:47 pm (0547 GMT) today that the US military's Osprey crashed off Yakushima Island," a spokeswoman had told AFP.

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 Osprey aircraft 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.

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

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Last year, four US Marines were killed in Norway when their MV-22B Osprey jet crashed during NATO training exercises. The drill featured 30,000 soldiers from 27 nations and is presented as a "defensive" exercise.

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.