The vessel went down while operating in bad weather in the East Sea, the Vietnamese Foreign Ministry said, adding that all 48 rescued people had been transferred to Vietnamese authorities.
A Chinese rescue vessel first spotted what was believed to be a distress signal from the endangered ship shortly before 6:30 pm on Saturday (1030 GMT), state news agency Xinhua said.
Beijing claims sovereignty over almost the entire South China Sea, a vital global trade route, despite an international ruling that found its claims have no legal basis.
