The South Korean government ordered on Tuesday urgent safety inspections at high-risk industrial sites a day after a fire at a lithium battery factory that killed 22 workers with one person still missing.

Officials from agencies including the National Forensic Service, police and the fire department entered the factory as part of a joint investigation.

The blaze which broke out inside a warehouse with 35,000 lithium batteries produced toxic smoke, and the workers likely lost consciousness and succumbed within seconds, fire officials have said.

The fire was the latest industrial accident in a country where dozens of manufacturing workers lose their lives on the job each year despite repeated calls to improve workplace safety.

"I ask the ministries of labour and industry and the National Fire Agency to conduct an urgent safety inspection and, where there is concern of an accident, take immediate measures," Prime Minister Han Duck-soo said at a cabinet meeting.

Seventeen of the 22 workers who died were Chinese and one Laotian was also among the dead. Most of them were hired temporarily to work at the plant packing primary lithium batteries run by unlisted company Aricell.

The factory is in Hwaseong, an industrial cluster southwest of the capital Seoul.

Firefighters with search dogs combed the gutted structure looking for the one person who remains missing. They found human remains and personal articles, which will be DNA tested for identification, Hwaseong fire official Kim Jin-young said.

Regulatory filings showed Aricell recorded a 2.6 billion won ($1.9 million) operating loss last year on 4.8 billion won revenue, and a 14% increase in accumulated debt to 23.8 billion won. It has recorded net losses every year since founding.

Shares of S-Connect, registered on the junior Kosdaq index, were trading down 6% on Tuesday after plunging 22.5% on Monday following the news of the fire.

A labour ministry official told Reuters it was investigating whether Aricell complied with safety regulations and gave enough safety training for temporary foreign workers. Violations of those regulations are subject to criminal prosecution, the official said requesting anonymity.

Many of the bodies remain unidentified.

Reuters journalists saw some wailing family members trying to enter the site, which had been cordoned off.