China has asked Vietnam to seriously investigate a recent robbery of some of its fishing vessels by Vietnamese fishermen in the Beibu Gulf.

"China is highly concerned about the case, and has made representations to Vietnam and required the Vietnamese side to seriously investigate and handle the case, and at the same time, take effective measures to avoid further cases," said Chinese Foreign Ministry spokeswoman Jiang Yu at a regular press conference on Thursday.

According to Jiang, on January 7, some fishing vessels from south China's Hainan Province were robbed by armed Vietnamese fishermen amid normal operations in the Beibu Gulf, situated in the northern part of the South China Sea, leading to lost property.

She said Vietnam promised to coordinate with China in the investigation into the robbery.

"We are ready to make joint efforts with the Vietnamese side to safeguard stability in the Beibu Gulf and the immediate interests of the fishermen living along the gulf."