In its complaint, Google claimed Microsoft and Nokia, which cooperate on smartphone technology and production, transferred 1,200 patents for assertion to a group called MOSAID, which the company called a "patent troll" - a term referring to a holder of patents that litigates them aggressively.

"Nokia and Microsoft are colluding to raise the costs of mobile devices for consumers, creating patent trolls that side-step promises both companies have made," the Internet search leader said in a statement, adding that the complaint was filed "recently."

"They should be held accountable, and we hope our complaint spurs others to look into these practices."

Microsoft said the complaint was a "desperate tactic" by Google.

"Google is complaining about antitrust in the smartphone industry when it controls more than 95 percent of mobile search and advertising," Microsoft said in an emailed statement.

"Google is complaining about patents when it won't respond to growing concerns by regulators, elected officials and judges about its abuse of standard-essential patents," Microsoft said.

Nokia was not immediately available for comment.

(Reporting by Edwin Chan in San Francisco and Bill Rigby in Seattle; additional reporting by Bijoy Koyitty in Bangalore.; Editing by Gary Hill, Matthew Lewis and Richard Pullin)

• A Permanent Economic Emergency