Seoul,   The South Korean labour ministry raided an air conditioning component manufacturer in the southern city of Changwon over suspected violations of the workplace disaster prevention law after 16 workers were diagnosed with acute poisoning with a hazardous substance.

It is the first alleged workplace disaster offence involving industrial diseases. Previous labour ministry probes mainly involved workplace accidents.

The raid into Doosung Co came after acute chloroform intoxication was reported in the 16 workers showing liver function problems after they were exposed to as high as six times the normally permitted level of the chemical during a product cleansing process.

Following the finding, the labor ministry ordered an immediate halt to the cleansing process, reports Yonhap news agency.

Chloroform, also known as trichloromethane, is a colourless, volatile liquid. When inhaled by humans at a concentrated level, it can damage the liver.

"Acute poisoning happened in more than 10 workers at the same time from the same cause," a ministry official said. "As this is a very serious case, we conducted the raid swiftly."

Officials wrapped up the search in about 12 hours and seized documents regarding the company's management of chemicals and overall safety measures.

The ministry also launched a probe into a company that supplies the liquid to Doosung, the official added.