(Reuters) -Apple said on Friday it has approved Epic Games' games marketplace app on iPhones and iPads in Europe, after the "Fortnite" maker escalated its feud with the technology giant, accusing it of hindering its efforts to set up a games store on the devices.

Apple said the latest spat concerned the Epic Sweden AB Marketplace and has nothing to do with the video games maker's Fortnite app which has already been given the green light.

Apps developers and antitrust regulators have criticized Apple's tight control of the iOS app ecosystem.

Before Apple's announcement, Epic said the iPhone maker had twice rejected documents the video-game publisher submitted to launch the Epic Games Store because the design of certain buttons and labels was similar to those used by its App Store.

"We are using the same "Install" and "In-app purchases" naming conventions that are used across popular app stores on multiple platforms, and are following standard conventions for buttons in iOS apps," Epic said in a series of posts on X.

"Apple's rejection is arbitrary, obstructive, and in violation of the DMA (Digital Markets Act), and we've shared our concerns with the European Commission," it said.

The European Commission, which opened an investigation into the checks and reviews put in place by Apple to validate apps and alternative app stores to be sideloaded last month, declined to comment.

Epic and Apple have been waging a legal battle since 2020, when the gaming firm alleged Apple's practice of charging up to 30% commissions on in-app payments on its iPhone Operating System (iOS) devices violated U.S. antitrust rules.

Early this year, Apple proposed changes to its App Store policies to comply with certain directives of the DMA that went into force in March.

It allowed alternative app stores on iPhones and an opt-out from using the in-app payments system, but set a "core technology fee", which several developers found exploitative.