The Tokyo High Public Prosecutor's Office is conducting a sweeping investigation of a number of public engineering companies on charges of violating the Antimonopoly Law over the years by restricting fair business transactions. Public prosecutors have launched the massive investigation in response to a criminal complaint filed by the Fair Trade Commission against repeated bid-rigging in steel bridge-related construction projects ordered by the Ministry of Land, Infrastructure and Transport's regional development bureaus in Kanto, Tohoku and Hokuriku.

The steel-bridge construction market is said to amount to 350 billion yen a year, so this could turn out to be the largest bid-rigging scandal ever. The FTC's action was the the first in almost two years -- since it filed a similar complaint over bid-rigging in connection with water-meter contracts ordered by the Tokyo Metropolitan Government in 2003.

The bid-rigging is believed to have occurred through two organizations formed by companies specifically for such illegal activities. They are suspected of having engaged in bid-rigging for about four decades under certain rules, including one that decided the allotment of construction work according to past performance in receiving orders.