Google has been issued formal antitrust charges over claims that it abuses the dominant position of its Android operating system.
The European Commission sent a statement of objections to the tech firm, alleging that it has breached EU competition law.
Google is accused of placing onerous requirements on firms using Android and stifling competition.
It said Android was “good for competition and good for consumers”.
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.”
Speaking at a press conference in Brussels on Wednesday, the European competition commissioner, Margrethe Vestager, said she had reached a preliminary view that Google was in breach of EU law.
It has been given 12 weeks to respond, and, if found guilty, the company faces a fine and could be required to change its practices.
Ms Vestager said Google had harmed both competitors and consumers by placing requirements on mobile manufacturers and operators to preinstall some of its own products and, in some cases, set them as default or exclusive options on handsets.
In some cases, she said, this had been as a condition of Google’s agreement to grant a licence for the use of some of its apps.
Android is open-source software, meaning competing operating systems can be built using its source code.