“At the current stage of the proceedings, we are unable to provide more information about the ongoing criminal proceedings”, the statement said.

The event took place on Monday at the battery factory being built by Korean company SK Innovation.

A substance was released into the air, which dozens of people inhaled and became sick, vomited and had diarrhoea, and several developed rashes, Szabad Európa reports.

One source said those involved had been working without protective clothing with heavy metals such as cobalt and nickel, after which they became ill.

The factory managers sent those involved for medical examinations, but ordered a strict news blackout.

Photo: Market Építő