Wreckage from a Japanese F-35A stealth fighter jet has been found a day after it disappeared off the radar over the Pacific, the country's defence minister said Wednesday.

There was no word yet on the fate of the one pilot on board the jet, Defence Minister Takeshi Iwaya said.

It was the first reported case of a crash by an F-35A, according to Japan's Air Self-Defence Force.

"We have collected part of its tail" in search operations at sea with planes and vessels, Iwaya told reporters.

"We believe it crashed," he added.

The fighter jet went missing around 7.30 pm (10.30 GMT) Tuesday as it was flying some 135 kilometres (85 miles) east of Misawa, northeastern Japan, on a training mission.