The Diet passed a measure Wednesday to toughen the Antimonopoly Law, increasing penalties for companies that rig bids, form cartels or engage in other illegal trade practices.
The law will take effect as early as January, when the penalty or surcharge on a large manufacturer will be increased to 10 percent of sales for a product subject to an illegal practice, up from the present 6 percent.
Surcharges will be reduced or removed for companies that voluntarily report illegal practices.
The House of Councilors passed the bill in a plenary session. It was approved March 15 by the House of Representatives.