Firemen appear to have quelled a blaze of an oil tanker in waters just off Hong Kong on Tuesday, but there are fears the vessel – listing badly after the fire – could pose an environmental hazard.

Steven Ho Chun-yin, a Legislative Council member who covers agriculture and fisheries, urged the government to disclose more information about chemicals that the vessel may have carried.

Ho said nearby fishermen were worried that their aquaculture farms would be polluted.

At least one man died and two others are missing after the tanker caught fire off, sending a huge cloud of dark smoke billowing into the air. The victims and most of the crew are thought to have been Vietnamese.

The Aulac Fortune is an oil and chemical tanker registered in Vietnam. It is reported to have left Dongguan, an industrial city in southern China, on Monday and arrived at the South Lamma anchorage at about 3am.

Nearly two dozen crew members were rescued after jumping into the sea near the vessel while the fire was raging, a police spokesperson told Agence France-Presse.

A number of the victims suffered burns, and the government said two injured men were taken to hospital.

“I felt my boat shaking. The tremble came from the sea,” said speedboat driver Michael Kwok, who told AFP he heard three explosions while out on his boat nearby.

Hours after initial reports of the oil tanker catching fire in waters south of Lamma Island, emergency services were still battling to contain the blaze and any spillage from the vessel.

A Hong Kong government statement said firefighters were using four jets to contain the blaze, and a fireboat was seen spraying two streams of water into the sea near the tilted side of the tanker, which had a mass of twisted metal on the deck and a charred exterior wall.

Three more fireboats, a helicopter and a police boat were also circling the scene.

“I heard several banging and rumbling sounds, like someone with big hands knocking my glass door,” a resident of Lamma Island’s Mo Tat New Village, who gave his name as Shu, told AFP. A smaller banging sound followed about 10 seconds later.

‘Ball of fire’

A fisherman from Lamma Island told local news channel i-Cable he first heard explosions and then saw “dense smoke” followed by a “ball of fire”.

The MarineTraffic.com website listed the tanker as registered in Vietnam.

It is believed the tanker was carrying chemicals as well as oil, with ship-tracking websites MarineTraffic and VesselFinder both classifying the ship as an “oil/chemical tanker”.

Police said there were 26 crew members onboard prior to the drama. Most of the surviving crew members sustained light injuries, according to i-Cable, which showed footage of some wrapped in silver heated blankets and walking up to ambulances without much assistance.