An Air Self-Defense Force search-and-rescue helicopter is believed to have crashed off Hamamatsu, central Japan, on Tuesday evening, Japanese Defense Minister Itsunori Onodera said.

The UH-60J chopper, carrying four crew, disappeared from radar at around 6 p.m. about 30 kilometers south of the ASDF's Hamamatsu base. Onodera said apparent helicopter debris had been seen floating in the ocean where it is believed to have gone down.

(Self-Defense Force)

"We've seen a door bearing the Air Self-Defense Force letters. We cannot help but believe that it crashed," Onodera told reporters.

The chopper left the Hamamatsu base at 5:50 p.m. to conduct a nighttime search-and-rescue drill. It disappeared from radar about 10 minutes later. The crew members included Maj. Akihiro Hanafusa, the 42-year-old captain.

Other ASDF helicopters, as well as Maritime Self-Defense Force vessels have been dispatched to the site to look for the missing crew members.