The pilot of a U.S. military fighter jet that crashed into the sea off northern Japan on Sunday has been rescued six hours after the accident, Japan's Coast Guard said.

The unnamed pilot was placed safely on a nearby U.S. container ship around 6 p.m., according to the agency, which sent ships and a plane to the accident site.

"The F-16 jet crashed some 470 nautical miles northeast of Nemuro" at around 11:30 a.m. local time, a spokesman at the Japan Coast Guard said earlier in the day.

The city of Nemuro is 1,000 kilometres north of Tokyo.

The U.S. Air Force said the pilot took off from Misawa Air Base in Aomori at about 11:30 a.m., heading for North America.

It added that the exact cause of the crash was under investigation. (From news reports)