Apple Inc. on Friday said it is suing cell phone maker Nokia Corp. for patent infringement, a countermove to Nokia's suit against technologies used in Apple's iPhone.
Apple's lawsuit claims Nokia is infringing on 13 of Apple's patents, and says the Finland-based company chose to "copy the iPhone," especially its user interface, to make up for its declining share of the high-end phone market.
A Nokia representative could not immediately be reached for comment Friday morning.
In October, Nokia filed a lawsuit in U.S. federal court claiming Apple, based in Cupertino, Calif., infringes on 10 of its patents.
Countersuits are a staple of patent litigation, which often ends in cross-licensing agreements.
Both suits were filed in federal court in Delaware.
U.S.-traded shares of Nokia rose 27 cents, or 2.2 percent, to $12.83 in morning trading, and Apple's shares slid 62 cents to $195.81.