The world's top mobile phone maker, Nokia, has launched another court case against Apple for alleged patent violations, in an increasingly fierce legal battle between two leaders of the smartphone market.

Nokia filed the case at a Delaware court in the United States on December 29 seeking damages for Apple's alleged infringement of seven Nokia patents in most of its products, court documents showed.

The suit coincided with a claim filed with the U.S. International Trade Commission (ITC) over the same patents, which Nokia alleged Apple infringed in virtually all of its mobile phones, portable music players, and computers sold.

Nokia needs the new case in Delaware to ask for damages as the ITC does not decide on financial compensation.

The seven patents in the two cases relate to Nokia technology being used by Apple to create features in user interface, camera, antenna and power management technologies.

Last year, both companies launched patent infringement suits against the other.

Nokia has stumbled badly in the fast-growing smartphone sector and relative newcomer Apple has gained a lot of ground against the market leader thanks to the iPhone, but still trails Nokia in smartphones sales.

Apple, which entered the industry in mid-2007, overtook Nokia in the September quarter as the cellphone maker generating the highest total operating profit.

The legal dispute, potentially involving hundreds of millions of dollars in annual royalties, reflects the shifting balance of power in the mobile industry as cellphones morph into handheld computers that can play video games and surf the Web.

(Reporting by Tarmo Virki; Editing by Hans Peters)

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