Eleven major plant engineering companies accused of rigging bids for sewage and sludge disposal plant projects created "how-to" bid-rigging manuals to facilitate the scam, investigative sources said Wednesday.
The documents have been circulating for years among executives involved in similar projects, the sources said.
On Tuesday, prosecutors arrested officials from seven major plant engineering companies, including Kubota Corp., Ataka Construction & Engineering Co. and Ebara Corp., on suspicion of unfair trade practices, in violation of the Antimonopoly Law.
Arrested were Kenichi Terakawa of Kubota, Shiro Umeda of Ataka, Tadayoshi Tsuji of Kurita Water Industries Ltd., Masanori Hasegawa of Ebara, Shinichi Usuda of JFE Engineering Corp., Kunio Tanno of Nishihara Environment Technology Inc., and Fumitake Nakamura of Hitachi Zosen Corp.