By Ben Klayman

DETROIT, Feb 15 (Reuters) - A wide-ranging probe of price fixing in a variety of car parts has expanded to product segments not yet disclosed, a top U.S. Department of Justice official said on Friday.

"The investigation is broader than what we've announced so far," Scott Hammond, deputy assistant attorney general in the antitrust division, told reporters in Detroit. He declined to provide further detail or predict when the probe would close.

Nine auto parts makers - Tokai Rika, Autoliv , TRW Deutschland Holding GmbH, Nippon Seiki Co Ltd, Fujikura Ltd, Furukawa Electric Co Ltd, Denso Corp, Yazaki Corp and G.S. Electech - have pleaded guilty.

The U.S. Justice Department is working with antitrust officials in Japan and Europe on the probe. It initially confirmed it was conducting a price-fixing investigation in February 2010 and has imposed $809 million in fines to date, including $470 million against Yazaki, Hammond said during a speech to the State Bar of Michigan.

Twelve people have pleaded guilty and 10, all from Japan, have surrendered to U.S. jurisdiction and are serving jail terms of one to two years, he said.

"It's still very much ongoing, but it already appears to be the biggest criminal antitrust investigation that we've ever encountered," Hammond said. "I say (it is) the biggest with respect to the impact on U.S. business and consumers, and the number of companies and executives that are subject to the investigation."

Hammond also said the investigation, which involves billions of dollars in commerce, could expand to new companies. "The investigation has grown in terms of the discovery of additional wrongdoing affecting additional products," he told reporters.

Automakers have cooperated in the probe, but he declined to provide further detail, Hammond said.

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