The labor ministry charged two executives of a petrochemical plant operator for violating the newly enacted workplace disaster law after an explosion at one of its factories in the southwestern city of Yeosu killed four workers and injured an additional four.

The ministry also sent a team of around 20 inspectors to the Seoul headquarters of the company, Yeochun NCC, on Friday to collect evidence potentially demonstrating a violation of safety regulations.

After Monday's raid of the company's field office in Yeosu and questioning of on-site officials, the ministry confirmed that there were insufficiencies in the overall safety management by the head office.

The Jeonnam Provincial Police have so far booked three people linked to the fatal explosion on charges of manslaughter due to professional negligence.