The Japanese government said Friday that a deep-sea search will begin next month for the two Maritime Self-Defense Force (MSDF) helicopters that crashed into the Pacific in April.

At the request of the defense ministry, the Japan Agency for Marine-Earth Science and Technology, or JAMSTEC, will begin the search using an unmanned deep-sea vehicle that can reach a depth of up to 6,000 meters, according to the science ministry.

The defense ministry on Tuesday declared dead seven crewmen listed as missing since the fatal collision of two MSDF patrol helicopters

The science ministry said JAMSTEC will use Deep Tow, a deep ocean floor survey system equipped with sonar and cameras, to search a wide area of the ocean floor.

The defense ministry on Tuesday declared dead seven crewmen listed as missing since the fatal collision of two MSDF patrol helicopters.

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The two SH-60K helicopters, each carrying four MSDF members, collided and crashed during a night drill on April 20 over the sea near Izu Islands, about 600 km south of Tokyo. Of the eight on board, only one body was recovered so far.

Flight recorders from both helicopters and pieces of the aircraft have been retrieved. But their main parts are believed to be lying on the seabed at a depth of about 5,500 meters, local media reported.