The Fair Trade Commission searched the offices of six water-treatment plant makers Tuesday looking for evidence of bid-rigging on local government contracts, investigation sources said.
The companies targeted were Sumitomo Heavy Industries Ltd., Kurita Water Industries Ltd., Ataka Construction & Engineering Co., Kubota Corp., Nishihara Environment Technology Inc. and Takuma Co.
It is the first time the antitrust watchdog has served a court-issued search warrant on a firm since the revised Antimonopoly Law took effect in January.
The searches, conducted with the special investigation squad of the Osaka District Public Prosecutor's Office, will continue Wednesday.
The FTC is expected to file criminal complaints with prosecutors against the companies in connection with bid-rigging on five projects in February and March 2005.
These include one ordered by the city of Hannan, Osaka Prefecture, and others by Shizuoka, Fukuoka and Kumamoto prefectures.
The FTC suspects the companies have been rigging bids for local government contracts for about 30 years.
Tuesday's searches are part of the FTC's investigations into 11 major water-treatment plant makers, which include Ebara Corp.and JFE Engineering Corp.