The demands made by Apple on networks selling its iPhone and iPad devices are being scrutinised by European regulators.
The European Commission yesterday said it was monitoring the issue amid concerns over the terms Apple imposed on firms that carry its products.
Several operators are understood to have complained to the Commission. One source told Reuters: "Apple insists on a certain level of subsidies and marketing for the iPhone".
A spokeswoman for Apple said: "Our contracts fully comply with local laws wherever we do business, including the EU."