The fisherman, whose identity is not known yet, died of gunshot wounds following a confrontation between a Malaysian Coast Guard vessel and two Vietnamese fishing boats off the northeastern state of Kelantan on Sunday, the ministry's spokeswoman Le Thi Thu Hang said in a statement on Monday night.

The fishing boats and the remaining Vietnamese fishermen are being held by Malaysian authorities who have accused them of illegally fishing in Malaysian waters, Hang said.

The Malaysian Maritime Enforcement Agency said 18 fishermen have been taken in.

The foreign ministry’s consular department, which is in touch with the Malaysian embassy in Hanoi, has expressed grave concern over the serious incident and asked Malaysian authorities to investigate and take action against those responsible for killing the fisherman and treat Vietnamese fishermen humanely.

"The ministry will also work with agencies in Vietnam to verify the identities of the fishermen and seek more information on the case to take necessary measures to protect the rights and legitimate interests of Vietnamese fishermen," Hang said.

News agency AFP quoted Coast Guard chief Mohamad Zubil Mat Som as saying that one Vietnamese fisherman suffered gunshot wounds and was pronounced dead after being brought to shore and "we are saddened by this deadly incident."