Soldiers from Japan's Ground Self-Defense Force 1st Airborne Brigade take part in a joint military drill in Funabashi of Chiba prefecture on Jan 8, 2023. (PHOTO / AFP)

TOKYO — A Japanese Ground Self-Defense Force (GSDF) helicopter with 10 people on board disappeared from the radar on Thursday in waters off the southwestern prefecture of Okinawa, local media reported.

The UH-60 multipurpose chopper disappeared from radar at around 4:40 pm local time about 18 km northwest of an airport in Okinawa Prefecture's Miyakojima Island, according to public broadcaster NHK citing the defense ministry and other sources.

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The helicopter took off from Miyakojima before 4 pm and was scheduled to return to the island after 5 pm, according to the NHK.

Two pilots, two mechanics and six crew were on board and all were Self-Defense Force members, the GSDF said.

The coast guard dispatched four patrol ships to nearby waters to search for the helicopter, which belongs to a unit in the Kumamoto Prefecture and was engaging in surveillance activities, the report said.

Weather conditions were described as moderate when the ships arrived around 6:10 pm, it added.