Seoul: Eight parts suppliers for Korea Electric Power Corp. (KEPCO), the state power utility, and their 11 employees were referred to trials on Tuesday on charges of rigging bids worth about 670 billion won (US$454 million), the prosecution said.

According to Yonhap News Agency, the Seoul Central District Prosecutors Office reported that four employees from Hyosung Heavy Industries, HD Hyundai Electric, LS Electric, and Iljin Electric have been arrested and indicted on charges of violating the Fair Trade Act through bid rigging.

The four companies, which led the alleged collusion, along with four other small and medium-sized companies that participated in the illegal practice, were also indicted under the legal principle of dual punishment, the prosecution stated. Additionally, seven other employees of these companies have been referred to trials without detention.

The indicted companies are accused of unfairly restricting competition by colluding to set bid prices and pre-select successful bidders in 145 bids for gas insulated switchgear ordered by KEPCO from March 2015 to September 2022.

The involved companies, which hold a 90 percent share of the nation's gas insulated switchgear market, are suspected of earning at least 160 billion won in illicit profits through the alleged bid rigging worth 677.6 billion won.

Prosecutors believe that the alleged bid rigging by these companies raised their winning bid prices over seven years and six months, causing damage such as increased electricity bills to the general public.