Audio streaming service Spotify (SPOT) went on the attack on Tuesday against tech giant Apple (AAPL). Spotify's grievances are rooted in the 30% App Store fee Apple charges for in-app purchases.

Harry Clarke, associate general counsel and Spotify's lead competition lawyer, said in an interview with CNN that Spotify decided to go public with its concerns because it represents a more significant issue within Apple.

"We are talking about this because it is reflective of Apple's anti-competitive practices across the board," Clarke said.

Spotify does not want to give Apple 30% of its App Store businesses, which means the streamer can't sell audiobooks through the iOS app. Spotify created three new features to circumvent the issue. Spotify believed the new loopholes could function and stay true to Apple's policies, but the App Store rejected the additions.

The rejection forced the company to drop the possibility of offering audiobook sales in the iOS app. iOS users who peruse Spotify's audiobook offerings can click on titles they are interested in but are met with the message: "Want to listen? You can't buy audiobooks in the app. We know it's not ideal."

Audiobooks are available through the Spotify website and browser but not on the Spotify app.

When Spotify users go to the Spotify website, they are met with a pop-up that declares the availability of audiobooks while also jabbing Apple for their "anti-competitive behavior."

"And while we want to deliver a super awesome and easy user experience, Apple is once again standing in the way," the pop-up reads. "This time, their anti-competitive behavior is not only hurting listeners like you but authors and publishers, too."

Spotify has also launched, a website dedicated to showcasing how it claims Apple is being anti-competitive. In 2019, Spotify filed a formal complaint against Apple with the European Commission for abuse of dominance and anti-competitive behavior for music streamers. Spotify has yet to hear a formal decision from the European commission.

Speaking on the matter in an Oct. 25 press release, Spotify CEO Daniel Ek said, "Apple continues to dictate what online innovation looks like, doing serious harm to the internet economy, choking competition and the imagination of app developers." Ek also called for government intervention globally, stating, "Apple has shown time and again that it will not self-regulate and has no real incentive to change."

Apple has not formally addressed Spotify's claims, but a 2019 press release it did comment on Spotify's complaint to the European Commission. The press release stated that Apple has worked with Spotify since its launch and called Spotify's demands for Apple unrealistic.

"We're proud of the work we've done to help Spotify build a successful business reaching hundreds of millions of music lovers, and we wish them continued success," the press release read in part, adding, "After all, that was the whole point of creating the App Store in the first place."