Google has suffered a major blow in Russia, after a court sided with an earlier ruling that the ad giant had violated the country's anti-trust rules by having its services bundled on Android-based devices.

Last September, competing search engine—Yandex, which is headquartered in Russia—brought a successful complaint against Google bundling its products on Android phones and tablets. At the time, the Russian Federal Anti-Monopoly Service (FAS) ruled that users of Google's operating system shouldn't be lumped with the ad and search giant's other services.

On Monday, Moscow's Arbitration Court chucked out Google's appeal against that ruling, and said that it "fully supports" the earlier FAS decision. "Google['s] actions led to prohibition of pre-installation of apps of other producers," it added.

Google will now be required to change its business practices with smartphone makers in Russia, or else face a fine if it fails to adhere to the ruling.

Ars sought comment from Google on this story, but it hadn't got back to us at time of publication.

The Moscow court's decision to reject Google's appeal comes at a sticky time for the company, which has been the subject of a long-running alleged abuse of dominance probe in the EU, where the multinational commands roughly 90 percent of the search market.

It's been reported by Bloomberg that Google could imminently be hit with a so-called Statement of Objections from competition officials in Brussels over the company's Android OS. Ars has been hearing similar rumours in recent weeks.