The EU launched a wide-ranging antitrust probe against Google Tuesday over concerns that it is forcing out rivals in the lucrative online advertising market.
The investigation will "assess whether Google has violated EU competition rules by favoring its own online display advertising technology services", a statement said.
The probe narrows in on an important slice of Google's business model where over 80 percent of the giant's revenue last year came from advertising, or $147 billion (124 billion euros).
"We are concerned that Google has made it harder for rival online advertising services to compete" in display ad technology, said EU competition chief Margrethe Vestager.
At issue is Google's largely unnoticed, but highly dominant technologies that serve as an intermediary or broker between advertisers and publishers online.
The business was also at the heart of a recent case in France - brought by News Corp, French daily Le Figaro and Belgium's Groupe Rossel - that saw Google fined 220 million euros ($267 million).
As in France, the EU will try to determine whether Google gave preferential treatment to its own ad inventory technologies AdX and Doubleclick, but will also look at other aspects of its business.
Crucially, the probe will also look into Google's announced plans to prohibit the placement of third party "cookies" on its Chrome browser, a move that has angered some publishers and advertisers.
A Google spokesperson said the company "will continue to engage constructively with the European Commission to answer their questions and demonstrate the benefits of our products to European businesses and consumers."
