Japan's fair trade watchdog plans to file a criminal complaint against nine electronics firms, including industry giants Hitachi Ltd. and Toshiba Corp., accusing them of rigging bids on public projects, Japanese media reported Monday.

The criminal complaint would meet demands by the United States that Japan crack down on widespread bid-rigging, which American officials consider an example of the Japanese market's inhospitability to outsiders.The case involves electronic equipment for sewage systems contracted by the Japan Sewage Works Agency, an affiliate of the Construction Ministry.

The nine firms are suspected of dividing the equipment contracts among themselves through a "draft" similar to those held in professional sports.

With the assistance of the agency, the companies fixed their bids so that each contract was won by the company that selected it in the draft, according to Japanese news reports. Bidding is supposed to be secret, to encourage competition for the lowest price.

The Yomiuri Shimbun, Japan's largest newspaper, and Kyodo News Service said the Fair Trade Commission would file a criminal complaint against the nine companies as early as January.

That is the strongest measure the commission can take. Prosecutors normally would follow it up by filing charges in court against the accused companies and their executives.

The commission had no comment on the reports, saying its investigation against the companies continues. The agency and the companies also had no comment. Agency chief Itaru Nakamoto told Kyodo he heard from former agency executives that the charges were false.

The case has received prominent play in the Japanese media because it indicates that bid-rigging, already known to be common in the construction industry, is also prevalent in other major industries.