The fishing boat, Lujiao Yu, capsized about 100 miles south of the South Korean island of Jeju, the South Korean Yonhap news agency said.

The fishing boat overturned in international waters and coast guard officials said the crew onboard the 16,400-ton Korean freighter rescued two sailors clinging to the sinking vessel.

Rescue efforts were under way Monday morning and officials said they did not know the immediate cause of the accident.