Korean National Police Agency has been embroiled in a controversy over an anonymous claim that it dispatched a strike unit to Monday's deadly battery plant fire site without gas masks.

Police told local media that the controversial action was due to the officers being deployed in the area that was over 100 meters away from the battery plant in Hwaseong, 45 kilometers south of Seoul.

A person claiming to be a member of the police special operation unit said Tuesday that the unit had been sent to the site of the fire wearing just a disposable KF94 mask. That is the type of mask used by ordinary members of the public in times of sickness or high levels of air pollution, and was not designed to protect against hazardous gases.

"(The police) sent the officers to the deadly fire site contaminated with hazardous materials and smoke, telling us to go to the hospital if we're not feeling well. ... I guess these incidents will pile up and make us ill years in the future, thanks to the leadership that won't even give us minimal equipment," the person wrote on Blind, an anonymous mobile community for workers here.

Gyeonggi Nambu Provincial Agency reportedly dispatched 70 members of the special operations unit at around 12 p.m. on Monday, about an hour and 30 minutes after the fire broke out. The officers were deployed at the site overnight until 7 a.m. the next day.

Police told local media that it initially instructed the unit to use gas masks, but decided wearing the gear was unsuitable since they were sent to an area that was 150 meters away from the plant fire. As a result, "some officers" were wearing KF94 masks on the job.

Officials added that dust masks were distributed to the officers on site at around 6:30 p.m. on Monday.

Monday's fire at the lithium battery maker Aricell's plant left 23 dead and eight injured, two of them seriously. The deceased were factory workers, most of whom had been trapped inside the three-story building after the fire that is thought to have been caused by exploding batteries.

The bodies of the trapped workers were found on the second floor of the plant where the fire started. Seventeen of the victims were Chinese and six were South Koreans, including one naturalized South Korean originally from Laos.