A U.S. federal jury on Friday found four companies, including Japan's Mitsui & Co. and a subsidiary, liable for involvement in a decade-long international plot to fix the price of a vitamin used as an animal feed supplement, a verdict that could result in damages of $147 million.

The jury found that Mitsui and its Ohio-based Bioproducts unit conspired with two other firms between 1988 and 1998 to fix the price of vitamin B-4, known as choline chloride, with other North American and European producers, according to a law firm working for the plaintiffs.

In the case heard in the U.S. District Court for the District of Columbia, the jury ordered the four companies, which include DuCoa LP and its owner, DCV Inc., to pay a total of $49 million. The damages will be tripled under U.S. antitrust laws.

An official with Mitsui & Co. (U.S.A.) in New York said, "We continue to believe that the allegations in this case are completely without merit and have asked the court to overrule the verdict."

Mitsui has denied being involved in the price-fixing conspiracy and refused to be part of a $1 billion settlement of class-action suits filed by purchasers of the vitamin.