BRUSSELS (AP) — The European Union's executive hit Google with an official antitrust complaint on Wednesday that alleges the company abuses its dominance in Internet searches and also opened a probe into its Android mobile system.

The move massively raises the stakes in the highest profile antitrust case in Europe and could lead to billions in fines for Google if it does not change the way it does business in the 28-country bloc.

In announcing the action, EU Competition Commissioner Margrethe Vestager said she is "concerned that the company has given an unfair advantage to its own comparison shopping service."

Vestager said the separate antitrust probe into Android will investigate whether the Internet giant relies on anti-competitive deals and abuses its dominant position in Europe's mobile market.

The EU has for years sought a settlement with Google, but says the company has not fully addressed its concerns.

The more confrontational route could mean years of legal wrangling — as well as fines worth billions. The EU can impose fines of 10 percent on annual revenue, or some $6 billion, and force the Mountain View, California, company to overhaul its system for recommending websites in Europe.

Vestager said her chief goal was to make sure multinationals "do not artificially deny European consumers as wide a choice as possible or stifle innovation."

The company has a market share of over 90 percent of Internet searches in the EU, compared with around 70 percent in the U.S. Vestager said that one in four companies complaining about Google were U.S. rivals.

"Dominance as such is not a problem," said Vestager. "However dominant companies have a responsibility not to abuse their powerful market position."

Google's general counsel Kent Walker wrote late Tuesday that a "statement of objections" to Google's business practices was to be released by Vestager Wednesday.

Thomas Vinje, legal counsel for FairSearch Europe, a group that has been urging EU regulators to rein in Google, said that Wednesday's move was "a significant step towards ending Google's anti-competitive practices, which have harmed innovation and consumer choice."