A crew member has died and two more were in a coma after a suspected case of gas poisoning on a Taiwanese bulker in Vietnam.

The incident took place on Sunday on the 32,000-dwt open-hatch vessel Vigor SW (built 2009) at Nghi Son International Port.

VN Express cited the border guard command of Thanh Hoa Province as saying on Tuesday that the three seafarers were Chinese nationals.

The Panama-flag ship was docked at the time. During unloading operations, the master discovered three colleagues unconscious.

They were named as Zhuang Lijn, 52, Li Wen Liang, 33, and Kong Deshan, 23.

The trio was taken to hospital, but one later died.

Another suffered broken ribs.

Doctor Duong Tat Linh, director of Hop Luc International General Hospital, said it is possible that the crew members had been poisoned by hydrogen sulphide.

The gas is often produced from the microbial breakdown of organic matter in the absence of oxygen, such as in swamps, sewers or a ship's cargo hold.

The border guard said it is working with other agencies to investigate the accident.

The bulker is owned by Taiwan’s Shih Wei Navigation, which has been contacted for comment.

The ship has a clean port state control detention record.