HELSINKI, FINLAND: 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 last week 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.

The seven patents at issue relate to Nokia technology being used by Apple to create features in user interface, camera, antenna and power management technologies, it said in a statement.