Reuters reported on Friday that the Federal Trade Commission (FTC) is looking into whether it's legal for Apple to continue taking a 30 percent cut from sales within rival music streaming apps now that the company has its own music streaming service.

No formal investigation has been launched, but one anonymous source speaking to Reuters said that the FTC “has had meetings with multiple concerned parties” to discuss the issue.

Two other anonymous sources said that the FTC is exploring antitrust concerns related to restrictions that Apple places on its rivals, including “a prohibition on advertising in the app that the company is on other platforms, a ban on marketing in the app that consumers can also buy directly from the company’s website, and a ban on linking to a company’s website from within the app.”

An FTC spokesperson told Ars that “FTC investigations are non-public and we do not comment on an investigation or the existence of an investigation."

Apple takes 30 percent from all in-app purchases made on iOS. For music streaming services, customers can often sign up on a Web browser to circumvent Apple's tariff and make sure that the streaming service gets all of the proceeds, but Apple prevents companies from letting their customers know that in the app.

This has been the case for years, but since Apple launched Apple Music last week, regulators may see a conflict that could give Apple an unfair advantage in the industry.

Reuters says that although Google also has a music subscription service and also charges 30 percent for in-app purchases on rival music streaming apps, its rules for those apps are less restrictive and have caused less controversy among competitors.

Apple recently lost a bid in the Second Court of Appeals to overturn an earlier ruling that said that Apple was liable in a price-fixing case involving five of the largest publishers in the US. In order to compete with Amazon's discount pricing, Apple let publishers set their own prices and took a fixed percentage of those sales. Circuit judges agreed that Apple then convinced publishers to influence Amazon's price scheme, which resulted in higher prices for customers.