Apple is abusing its position as gatekeeper to the App Store by blocking the latest version of Spotify's iOS app, according to a letter allegedly sent from the streaming company to Apple general counsel Bruce Sewell. A report claims Spotify general counsel Horacio Gutierrez is "causing grave harm to Spotify and its customers" by rejecting the iPhone app update, with Apple's billing system being at the heart of the complaint.

The letter received by Recode notes Apple declined the app citing "business model rules," and urging Spotify to use Apple's own billing system if "Spotify wants to use the app to acquire new customers and sell subscriptions." It is noted that the letter, sent to Sewell on June 26, has also been distributed to some Congressional staff in Washington, leading to Senator Elizabeth Warren yesterday criticizing major tech companies over such anticompetitive practices.

Gutierrez claims the denial of the latest update "raises serious concerns under both US and EU competition law. It continues a troubling pattern of behavior by Apple to exclude and diminish the competitiveness of Spotify on iOS and as a rival to Apple Music, particularly when seen against the backdrop of Apple's previous anticompetitive conduct aimed at Spotify. We cannot stand by as Apple uses the App Store approval process as a weapon to harm competitors."

Spotify has been a long-time critic of Apple's policy, which forces all in-app purchases, including subscriptions, to use its payment system, with Apple taking a cut as a transaction fee. To counter this, Spotify charges more for its subscriptions started on iOS than on other platforms, and has previously taken to contacting app users to convince them to change payment methods, something Apple bans services from advertising within the apps themselves.

A recent attempt to revive a promotion, where new subscribers can use Spotify for three months for $1 via Spotify's website instead of an in-app subscription, is thought to be one of the reasons behind the latest quarrel. While Apple threatened to pull the Spotify app if the music-streaming service continued telling iPhone users they could save money using the promotion, Spotify later complied with the demand, but then turned off App Store billing completely.