Defense Minister Gen Nakatani said a search was underway for a 33-year-old after the Ukushima went up in flames on Sunday in waters off southwestern Fukuoka.

The ship's other crew members, around 40 people, were rescued -- including one injured person -- officials said.

The Japan Maritime Self-Defense Force cancelled a mine warfare exercise as well as a joint minesweeping drill with the United States to focus on the search.

A dozen naval ships joined coastguard vessels and dive teams to look for the missing sailor, Nakatani said.

Officials believe the fire started in the ship's engine room.