Google has been accused by the European Commission of "stifling competition" by abusing the dominant position of its Android operating system.
The EU Anti-Trust Commission has alleged the technology giant has breached competition rules by preventing consumers from "having as wide a choice as possible".
In a statement of objections, the commission said Google was making manufacturers pre-install Google Search and the Chrome browser.
It said the tech firm also made manufacturers set Google Search as a default service on their devices to gain access to certain Google-owned apps.
It added that Google was giving financial incentives to manufacturers and mobile network operators if they exclusively pre-installed Google Search on their devices, while blocking some manufacturers from selling smartphones which ran on "competing operating systems based on the Android open source code".
The commission said it was concerned that these moves could stop other mobile browsers from being able to compete with Google Chrome in the rapidly growing smartphone market.
Margarethe Vestager, commissioner in charge of competition policy, said a "competitive mobile internet sector" was becoming more important for consumers and businesses in Europe.
She added: "Based on our investigation thus far, we believe that Google's behaviour denies consumers a wider choice of mobile apps and services and stands in the way of innovation by other players, in breach of EU anti-trust rules.
According to the EU Commission, Google is a dominant force, holding more than 90% of the market for general internet search, licensable smart mobile operating systems and app stores for the Android mobile operating system.
It added that about 80% of smartphones across the world run on the Android operating systems developed by Google.
The rebuke from the commission comes after Google faced criticism earlier this year for the amount of tax it pays in the UK.
The company has agreed to pay the Treasury £130 million in back taxes and interest dating back to the previous decade, but has been criticised over the amount.
Kent Walker, Google's senior vice president and general counsel, said: "Android has helped foster a remarkable - and, importantly, sustainable - ecosystem, based on open-source software and open innovation.
"We look forward to working with the European Commission to demonstrate that Android is good for competition and good for consumers."