The European Commission has launched an in-depth investigation into Apple's takeover of UK-based music app Shazam after finding the deal could raise competition concerns.
Apple revealed in December that it was snapping up the song recognition tool in a deal reportedly worth $400m (£286m).
Shazam allows users to identify songs by pointing a smartphone or tablet at speakers playing music.
The European Commission said it was concerned that the takeover could see rivals' music streaming services put at a competitive disadvantage to Apple Music.
This is because Apple would obtain commercially sensitive data about its rivals' customers by owning Shazam, according to the EC's initial findings.
Those rivals include Spotify, the global market leader.
"Access to such data could allow Apple to directly target its competitors' customers and encourage them to switch to Apple Music," the EC said.
The in-depth investigation will also looking into whether rivals would be harmed "if Apple, after the transaction, were to discontinue referrals from the Shazam app to them".
Commissioner Margrethe Vestager said: "The way people listen to music has changed significantly in recent years, with more and more Europeans using music streaming services.
"Our investigation aims to ensure that music fans will continue to enjoy attractive music streaming offers and won't face less choice as a result of this proposed merger."
The Commission now has until 4 September to take a decision on the deal.
Apple said when announcing the takeover in December that Shazam would be a "natural fit" with its Apple Music streaming service and would help users discover new songs.
Digital services are increasingly important to Apple as iPhone sales slow.
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Shazam was founded in 2002 and made one of the first apps for the iPhone.
It has about 250 employees at its London headquarters and seven other offices in the US, Australia and Germany.