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TOKYO (Reuters) - The United States will begin an investigation into whether thermoplastic components used in some Japanese and German vehicle models sold in the country violate its patent laws, trade authorities said late last week.

The U.S. International Trade Commission (USITC) on Friday listed 25 companies in the probe, including BMW, Honda Motor Co Ltd, Toyota Motor Corp, along with Japanese parts suppliers Aisin Seiki Co Ltd and Denso Corp.

The probe was initiated by patent holding firm Intellectual Ventures II, which in March filed a complaint alleging that thermoplastic parts used in motors, water pumps, electronic power steering units and other powertrain parts made by or used in vehicles sold by the companies infringe on its patents.

Used in parts which come in contact with high-temperature auto components, thermoplastics are more lightweight and durable compared with other materials used in vehicle powertrains, helping to increase efficiency and improve fuel economy.

The complaint affects vehicle models sold in the United States including the 2016 Toyota Camry, 2017 Honda Accord and the 2016 BMW 228i, according to the patent company.

The USITC said it would set a target date to complete its investigation within 45 days of starting the probe.

Shares in Honda and Toyota were little changed during the Tokyo session on Monday.

A Toyota spokeswoman declined to comment on the issue, while officials in Japan at BMW, Honda, Aisin and Denso were not immediately available for comment.