Fortnite and Apple have been locked in legal battle since August
The UK’s Competition and Markets Authority has launched an investigation into whether Apple’s terms for app developers are anti-competitive.
It follows a series of complaints, including a high-profile one from Epic Games, the developer of Fortnite.
Some developers are unhappy that they are forced to distribute apps to iPhones and iPads via the App Store, and the commission Apple takes.
Apple said its terms were “fair and equal”.