Documents obtained by the Financial Times show that the European Commission has begun looking into whether Apple's agreements with carriers are illegal. The commission has expressed concern that the deals could ensure Apple's rivals cannot secure better sales agreements.
The investigation reportedly began after the commission received "private complaints from mobile operators." The commission's investigation remains preliminary, and no formal charges have been brought against Apple.
The investigation was brought to light by questionnaires sent by the commission to mobile operators across Europe. The nine-page document reportedly inquires whether carriers are being forced to buy a minimum number of iPhones, or if they are restricted on how to use their marketing budgets.
The document also asks whether Apple enforces any clauses on subsidies for handsets that compete with the iPhone, and it quizzes operators on whether contractual restrictions prevent the iPhone 5 from accessing high-speed 4G networks in Europe. Carriers have until June 17 to reply to the questionnaire.
Previous European Union investigations of Apple have taken a closer look at the company's warranty practices and the iPad maker's e-book deals with publishers. But those inquiries have not led to formal antitrust lawsuits.