The Japan Fair Trade Commission has filed criminal complaints against advertising giant Dentsu and other firms and individuals for alleged bid-rigging related to the Tokyo Olympics and Paralympics.

The move is expected to pave the way for prosecutors to indict the six firms and seven individuals on Tuesday for violating the anti-monopoly law.

Dentsu and others are suspected of unlawfully pre-arranging the winners of bids to plan and stage the Games' test events and run the actual competitions. The contracts reportedly totaled about 43.7 billion yen, or roughly 320 million dollars.

Prosecutors and fair trade officials believe the winners of the test-event bids signed discretionary contracts that included work for the actual events.

The six firms named in the complaints are Japan's largest ad agency Dentsu, second-largest Hakuhodo, Tokyu Agency, and event production firms Cerespo, Fuji Creative Corporation and Same Two.

The seven individuals include Mori Yasuo, who served as deputy director of the Tokyo Games' organizing committee's operations bureau, and former Dentsu executive Henmi Koji.