A little more than a week after the European Commission (EC), the executive arm of the European Union (EU), fined Google $2.73 billion for search engine-related antitrust violations, sources have said the tech company could face an even bigger fine for using its Android mobile operating system to gain a competitive advantage over rivals.

Citing "two people familiar with the matter," Reuters yesterday reported that Google faces a potential fine bigger than the one issued last month for alleged anti-competitive practices since 2011. In April 2016, the EC sent Google a Statement of Objections, which set in motion a formal investigation into the company's use of Android to limit competing browsers, operating systems, and search engines.

According to the Reuters report, European antitrust authorities have asked an expert panel to review the commission's findings against Google and offer a second opinion on last year's Statement of Objections.

EU: Google 'Abused Its Dominant Position'

"The EU's charge sheet issued to Google in April last year said the anti-competitive practices started from January 2011 and the Commission is likely to tell the company to stop them," Reuters reported. "They are still ongoing, telecoms industry sources said."

In launching its investigation last year, the EC said that Google had "abused its dominant position by imposing restrictions on Android device manufacturers and mobile network operators."

Google has done so by pre-installing Google Search and setting it as the default search service on most Android devices sold in Europe, according to the commission. That strategy appears to "close off ways for rival search engines to access the market, via competing mobile browsers and operating systems," the commission said. Google's actions "also seem to harm consumers by stifling competition and restricting innovation in the wider mobile space," according to the EC.

Another Group Joins Complainants

Complaints from several organizations, including the U.S.-based FairSearch, caused the EC to investigate Google's Android practices. FairSearch was launched in 2010 as a joint effort by a number of travel companies, including Expedia and TripAdvisor as well as Google rival Microsoft.

In March, the Open Internet Project (OIP), another coalition of companies, lodged its own complaint with the European Commission about Google's Android practices. The group, which includes publisher Axel Springer, Funke Medien Gruppe, and the French search engine Qwant, said Google "abused its dominant position" to preserve its hold on Internet search.

"This new development is yet more evidence of the widespread concerns engendered by Google's abusive practices," FairSearch said in a statement after the OIP filed its latest complaint. "FairSearch supports the European Commission's efforts to require undistorted competition, and we urge the European Commission to conclude this case, and find Google liable for violating EU competition rules."

As the search engine case against Google concluded with last week's fine, the EC is pursuing two remaining investigations against Google: one centered on its Android practices, and the other involving its AdSense advertising services.

It's uncertain how long it might take the expert panel, called "a devil's advocate," to conclude its review of the European Commission's Android case, according to Reuters.