Three sailors were confirmed dead, and one remains missing, as a fishing boat sank off South Korea's southern coast, Yonhap news agency said Thursday.

The 139-tonne trawler with 11 crew members on board, including four South Koreans, six Indonesians and one Vietnamese, sank in waters off an island in Tongyeong, about 330 km south of the capital Seoul.

A distress call was sent to the coast guard at around 4:15 a.m. local time Thursday.