The transport ministry ordered two major contractors on Friday to temporarily suspend part of their business operations after they were fined last year by a Tokyo court for rigging bids for construction work on the Tokyo-Osaka maglev train project.

Under the order based on Japan's construction business law, Obayashi Corp. and Shimizu Corp. are prohibited from engaging in new construction projects for 120 days from Feb. 2. But they can continue to work on projects they have already started.

Last October, the Tokyo District Court ordered Obayashi and Shimizu to pay ¥200 million ($1.83 million) and ¥180 million in fines, respectively, for violating the antimonopoly law by colluding with two other major contractors, Kajima Corp. and Taisei Corp., in rigging bids.

A separate trial for Taisei, Kajima and two former executives of the contractors will start on Feb. 14 at the Tokyo District Court.

The four contractors had been suspended from bidding for projects ordered by the Land, Infrastructure, Transport and Tourism Ministry and others for four months from March last year.