Prosecutors on Monday arrested an executive at Japan Highway Public Corp. and indicted his former colleague and officials from four companies, stepping up their probe into one of the country's largest public works bid-rigging scandals.

The Tokyo District Prosecutor's Office arrested Tsuneo Kaneko, a 57-year-old executive board member of Japan Highway, in connection with the alleged bid-rigging for bridge projects ordered by the highway body in violation of the Antimonopoly Law, prosecutors said in a statement.

Kaneko is the second current executive of Japan Highway to be arrested, following the arrest of its vice president, Michio Uchida, on July 25.