A visitor passes the Google logo at the official opening...

A visitor passes the Google logo at the official opening party of the Google offices in Berlin, Germany. (Sept. 26, 2012) Credit: Getty Images

BT Group Plc's U.S. unit was sued by Google Inc. over claims it infringed four patents related to network communications including through voice-over-Internet services that BT Americas provides.

Google, owner of the world's most popular Internet search engine, filed a complaint Wednesday in federal court in Los Angeles. The Mountain View, California-based company seeks a court order preventing BT Americas from continuing its alleged infringements of the patents as well as unspecified damages.

BT, based in London, accused Google in a 2011 lawsuit of infringing six of its U.S. patents for mobile-device technology.

"BT has brought several meritless patent claims against Google and our customers -- and they've also been arming patent trolls," Niki Fenwick, a Google spokeswoman, said in an emailed statement Wednesday. "When faced with these kind of actions, we will defend ourselves." Kris Kozamchak, a BT spokeswoman, said Wednesday in an email that the company doesn't comment on pending litigation.

The case is Google v. BT Americas, 13-00254, U.S. District Court, Central District of California (Los Angeles).