SEOUL, June 19 (Xinhua) -- A South Korean navy solider was seriously injured Tuesday in a battleship explosion in waters off the country's southeast coast, Yonhap news agency and local broadcaster YTN reported.

The 1,500-ton Navy vessel, called Masan, conducted a firing exercise at about 12:20 p.m. local time (0320 GMT) in waters off the coastal city of Tongyong in South Gyeongsang province.

What was estimated to be an explosion happened inside the battleship. The exact cause of the accident was under investigation.

The injured soldier was taken by chopper to a nearby hospital, according to local media.