Apple countersues Nokia over patents

Apple has filed a patent lawsuit accusing Nokia of infringing 13 Apple patents, in response to Nokia's patent lawsuit against Apple filed in October.

Apple didn't detail what patents it has accused Nokia of infringing.

"Other companies must compete with us by inventing their own technologies, not just by stealing ours," Bruce Sewell, Apple's general counsel and senior vice president, said in a statement.

Neither Apple nor Nokia immediately respond to requests for comment.

In October, Nokia filed a patent lawsuit against Apple in U.S. District Court for the District of Delaware, accusing Apple of infringing 10 of its patents.

The patents have been used by Apple's iPhone since it was introduced in June 2007, Nokia said. The patents cover wireless data, speed encoding and decoding, security and encryption, the company said.

Nokia, the world's largest mobile handset maker, said it has invested nearly US$60 billion, in research and development over the last 20 years to acquire its patents.

Approximately 40 companies, but not Apple, have licensed those patents, Nokia said.