Apple's (AAPL -0.57%) App Store is attracting more controversy. On Thursday the Competition and Markets Authority (CMA), an antitrust arm of the U.K. government, disclosed that it has launched an investigation into the U.S. tech giant's business practices with the online store.

The CMA said it was doing so in the wake of both complaints from developers about those practices and the agency's own work in the digital sphere. These allege that Apple's fairly strict terms for developers to get their software into the App Store are not fair and possibly in violation of the country's competition law.

Man using smartphone.

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In other jurisdictions, such as the U.S., Apple has come under fire for the way it partners with developers in that marketplace. It takes a commission of 30% of all App Store sales and reaps similar fees for in-app purchases made by users. As the CMA pointed out in the press release announcing its investigation, the App Store is the only legitimate means for developers to distribute their offerings for Apple devices. It is also the only platform for Apple users to access them.

The CMA said that its investigation will focus on whether Apple's terms and conditions are unfair or anti-competitive to developers. It will also take into consideration whether user choice is consequently being restricted or if those customers are paying unacceptably high prices for apps and add-ons.

"Millions of us use apps every day to check the weather, play a game or order [takeout food]," the CMA quoted its chief executive Andrea Coscelli as saying. "So, complaints that Apple is using its market position to set terms which are unfair or may restrict competition and choice – potentially causing customers to lose out when buying and using apps – warrant careful scrutiny."