Corp., an arm of Sanyo Electric Co., has filed a lawsuit against Chinese firm BYD Co., accusing the company of infringing on patented battery technology, Sanyo Electric said Wednesday.

The lawsuit, also directed at the Chinese firm's U.S. arm, BYD America Corp., was filed at the U.S. federal district court in southern California, the Japanese electronics firm said.

Sanyo Energy, based in San Diego, is seeking a court injunction barring BYD America from selling and importing lithium ion batteries it says infringe on Sanyo's U.S. patents.

Sanyo Energy is also seeking damages from BYD. The patents relate to "the constitution of the bare cell of lithium ion batteries and the structure of the battery pack," the company said in a statement.

The lightweight rechargeable batteries have a high energy density and are used in notebook computers and mobile phones. Sanyo Energy has been assembling battery packs for the lithium ion batteries and selling them in the United States.

Sanyo Electric said it purchased, dissembled and scrutinized BYD's lithium ion batteries in September 2001. It maintains BYD pirated its technology.

BYD is based in Shenzhen, China.

Sanyo Electric began mass production of lithium ion batteries in 1994.

IT was founded in April 1987. The U.S. firm produces nickel-cadmium batteries and nickel-metal hydride batteries in addition to lithium ion batteries.