Coast guards rescue 13 crew members from the Jin Tian, but fears remain over their condition.
Eight crew members were reported missing after a Chinese general cargo ship sank off Japan on Wednesday 25 Jan.
Rescuers picked up another 14 seafarers, but nine of these were said to be unconscious.
The 9,800-dwt Jin Tian (built 2010) went down 110 km west of the Danjo Islands in the East China Sea.
A joint operation was launched by South Korea’s and Japan’s coast guards.
The Japanese side said five Chinese nationals were confirmed alive.
The captain last communicated with the coast guard through a satellite phone in the early hours of Wednesday, saying crew members would abandon the ship.
The vessel sank six minutes later, according to South Korean officials.
Six seafarers were rescued by South Korean coast guard vessels, while a cargo ship picked up another five and Japanese aircraft winched three more to safety
A distress call had been sent on Tuesday night.
The crew consists of 14 Chinese and eight Myanmar nationals.
The Jin Tian had been expected to reach the port of Incheon in South Korea on Wednesday. The ship left Malaysia’s Port Klang in early December, according to MarineTraffic.
The cause of the accident is not yet known. The cargo vessel is managed by Shenzhen Shekou Shipping & Transport of Guangdong, China.
It has a clean port state control detention record and is insured through the West of England P&I Club.