The EU's top anti-trust chief Margrethe Vestager said Monday she was taking aim at Google's Android mobile phone platform in a potentially major setback for the Silicon Valley giant.
In a speech in Amsterdam, Vestager said EU regulators "need to be sure that big companies don't try to protect themselves by holding back innovation."
"That's why we’re looking closely at Google’s contracts with phone makers and operators which use the Android operating system," she said.
The speech was the biggest signal yet that the European Union will file a formal statement of objections against Google after launching a probe into Android a year ago.
The case against Android would follow a similar one against Google's search engine in which the EU has already formally charged the company for abusing its dominance in Europe, where it controls about 90 percent of the market.
Android is by far the most used mobile operating system in the world and viewed as crucial to Google's future as customers increasingly rely on smartphones and tablets for their computing needs instead of traditional PCs.
In both cases, Google risks a fine of 10 percent of worldwide global sales for one year, which would reach about $7.4 billion for 2015.
In a historic case in 2013, the EU fined Microsoft 561 million euros ($634 million) for failing to offer users a choice of web browser.
Google in an email to AFP defended the Android system against accusations that it crowded out rivals.
"Anyone can use Android, with or without Google applications," said Google spokesman Mark Jansen.
"Hardware manufacturers and carriers can decide how to use Android and consumers have the last word about which apps they want to use on their devices," he said.
He added that company remained in discussion with the Vestager team.