A Chinese computer firm involved in a legal battle with Apple over the iPad trademark said Friday it is suing the technology giant in California for "unfair business and fraud".

Proview Technology, based in China's southern city of Shenzhen, filed the lawsuit a week ago on February 17, Proview Technology (Shenzhen) chief executive Yang Rongshan told AFP.

"The suit accuses Apple of unfair business and fraud," Yang said, adding the company was following a different legal strategy in the United States than in China, where it has sued for trademark violation.

He declined to give further details about the suit, filed in a state court near Apple's Silicon Valley headquarters.

The Wall Street Journal said the suit accused the company Apple of "fraud and/or malice" in using an innocuously-named subsidiary to buy the iPad trademark from Proview in December of 2009.

The case opens up another front for Proview, which suffered a legal setback on Thursday when a Shanghai court threw out a separate case against Apple and ruled the US company could continue iPad sales in the city.

The Shanghai case marked a victory for Apple in a protracted and ongoing legal battle with the debt-laden Proview over rights to the iPad name.

Proview's Taiwanese affiliate registered "iPad" as a trademark in several countries including China as early as 2000 -- years before Apple began selling its product.

The US titan subsequently bought the rights for global trademark, but Proview claims the Taiwanese affiliate had no right to sell the Chinese rights.

Apple last year took the firm to a Chinese court, claiming trademark infringement, but the court ruled the US company lacked "supporting facts and evidence" for its claim -- even though a Hong Kong court had previously sided with Apple.

Apple is now appealing that case, but Proview, which makes computer monitors, has itself filed trademark lawsuits against Apple in China.

At the same time, Proview has indicated an interest in a multi-billion-dollar cash settlement from Apple.