The case stemmed from a long-running Justice Department investigation of price fixing for graphite electrodes. Mitsubishi owned 50 per cent of UCAR International Inc, the world's largest producer of graphite electrodes, from early 1991 until early 1995.

UCAR pleaded guilty in 1998 to participating in a worldwide conspiracy to fix the price of graphite electrodes, paying a $110 million fine.

Graphite electrodes are the large columns used in electric arc furnaces to make steel in so-called "mini-mills." Nearly half of the steel in the United States is made using graphite electrodes. "We are extremely pleased that the jury found Mitsubishi guilty of participating in this international price-fixing conspiracy," acting assistant attorney general John Nannes of the Justice Department's antitrust division said.

"The jury's verdict sends a strong message that international cartels that target US consumers are not beyond the reach of the antitrust laws," he said in a statement.

Mitsubishi was charged in the case in January last year and issued a statement at the time denying the charges.