Google has accused Microsoft and Nokia of conspiring as “patent trolls” in an alleged bid to damage their smartphone rivals, including Google’s own Android.

In a formal complaint to the European Commission, Google accused the two of “colluding to raise the costs of mobile devices for consumers, creating patent trolls that sidestep promises both companies have made.”

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

The complaint was rebuffed by Microsoft, which described the move as a “desperate tactic.”

“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, and it is complaining about antitrust in the smartphone industry when it controls more than 95 percent of mobile search and advertising,” the software giant said in a statement.

Microsoft and Nokia formed their smartphone partnership last year, uniting behind Microsoft’s Windows Phone OS as an alternative to Android and others.

Google’s complaint alleges that its two rivals are using a proxy firm to assert their patents, which could force Android vendors to pay them royalties.

Nokia sold around 2,000 patents to a Canadian IP firm called MOSAID Technologies in September 2011. Approximately 1,200 of the patents and applications are deemed to be “essential” to the 2G (GSM), 3G (WCDMA) and 4G (LTE) standards.

MOSAID was acquired by the US private-equity group, Stirling Partners, the following month.