Google is already facing heavy fines from the European Commission, which said it used its popular Android mobile operating system to thwart rivals, an anti-competitive practice dating back to 2011.

Alphabet Inc’s Google is facing a new EU antitrust investigation into whether it may have forced device makers to use Google Assistant as the default voice assistant on Android devices, an MLex reporter tweeted .

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The latest investigation comes amid concerns about potential anti-competitive practices in the race for market dominance between Amazon’s Alexa, Apple’s Siri and Google Assistant.

Google is already facing heavy fines from the European Commission, which said it used its popular Android mobile operating system to thwart rivals, an anti-competitive practice dating back to 2011.

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Google did not immediately respond to a request for comment from Reuters.

The Commission declined to comment and referred to comments by EU antitrust chief Margrethe Vestager at a press conference on the results of an Internet of Things sector inquiry, during which respondents expressed concerns about the central role of voice assistants in smart devices and services and behaviors that negatively affect competition.

“Attempts to restrict the number of voice assistants accessible on smart devices are causing concern,” Vestager said.