The European Commission has sent a questionnaire to a mobile operators in the European Union, focusing on distribution terms that might favour Apple by ensuring no rival can secure a better sales deal, according to a newspaper report. "The Commission has information indicating that Apple and Mobile Network Operators ("MNOs") have concluded distribution agreements which may potentially lead to the foreclosure of other smartphone manufacturers from the markets," the nine-page questionnaire states, The Financial Times reported Sunday.

The commission needs to check whether European consumers are required to buy a minimum number of phones or whether operators are required to always offer Apple no worse subsidies and sales terms than other smartphone vendors. In addition, the European regulators are checking whether operators provide preferential treatment for marketing iPhones. There could also be a possibility that certain technical iPhone functions - such as 4G/LTE connectivity - were disabled on certain Apple products in certain countries in the EU and the European Economic Area, which if confirmed could constitute an infringement of antitrust law.

The deadline for replies is June 17.

Such questionnaires are a typical procedure in antitrust cases which helps the Commission determine whether to open a case against companies or reject complaints.

Apple said its contracts comply with EU laws, said the FT.

The inquiry is the result of private complaints from mobile operators and is at a preliminary stage.