CHITTAGONG: Toxic gas leaked from a vessel at a shipbreaking yard in Bangladesh on Friday, killing at least eight workers, with five others missing, police said.

Witnesses said they heard screams from inside the yard in the southeastern port city of Chittagong before workers rushed some of the victims to hospital.

Senior police official Abdul Kuddus Chowdhury said eight people had died and authorities were searching for the missing workers.

"A committee has been formed to investigate the incident, and the authorities have ordered an audit of the shipbreaking yard," Chowdhury told AFP.

The Ferdous Steel Shipbreaking Yard and Recycling Factory, which acquired the vessel previously used to transport liquefied natural gas, was listed as a "green" and compliant facility, he said.

But fire service official Towfiqul Islam Bhuiyan said safety procedures appeared to have been flouted, as the vessel should have been free of any gas before cutting began.

"The yard authorities did not follow the instructions. Workers who were exposed to the gas died, while those who were farther away survived," he told AFP.

Ferdous has not made any public comment about the incident.

Bhuiyan said firefighters recovered three bodies from the site and found several other workers unconscious, who were then taken to hospital.

Bangladesh's shipbreaking industry is spread along a 25-kilometre (15-mile) stretch of the Chittagong coast on the Bay of Bengal.

It is one of the world's largest shipbreaking hubs and employs tens of thousands of people.

The sector has long drawn scrutiny from labour and environmental groups over safety standards and working conditions.

Among the workers killed on Friday was Palash Jaladas.

His wife, Bhoumika Jaladas, who relatives said was eight months pregnant, was inconsolable.

"What shall I do now?" she told reporters.