Taiwanese smartphone maker HTC has filed a fresh lawsuit against Apple in the US, deepening the legal wrangle between the two companies.
In the latest case filed in Delaware's US District Court, HTC alleges that Apple infringed three HTC patents in devices including iPads, iPods, iPhones and Macintosh computers.
In July, Apple won a preliminary ruling from the International Trade Commission (ITC) when an administrative judge ruled HTC infringed two of four patents.
The full commission is to rule in December on whether it will uphold or reverse the preliminary ruling. Apple has also filed a parallel lawsuit against HTC in a court in the US District Court in Delaware.
The cases are part of a growing series of legal disputes between manufacturers in the fast-growing smartphone industry including Microsoft and Samsung.
HTC is attempting to strengthen its patent position through a series of acquisitions, most notably of S3 Graphics, a mobile video company that had itself won a preliminary ruling against Apple in the ITC court, according to the Financial Times.
The latest HTC suit says the company has acquired some of the patents at issue, which include one governing the interaction of personal digital assistants and wireless communications devices.