Three Japanese utility companies are under investigation on suspicion of price-fixing.
Officials of the Fair Trade Commission on Tuesday inspected the offices of Chubu Electric Power and its subsidiary, Chubu Electric Power Miraiz, as well as Toho Gas. All are based in Nagoya, central Japan.
The companies confirm the searches took place and say they are fully cooperating with the investigation.
Sources say the three coordinated their quotations for contracts with major customers, including factories, hotels and shopping centers in the region.
They say the firms' actions were aimed at swaying the selection of winning bidders. The sources believe the activities began four to five years ago.
Japan's retail energy market was fully liberalized in 2016. Competition has been intense ever since.