The European Commission will accuse Apple Inc <AAPL.O> of benefiting from illicit state aid inIreland, based on preliminary findings of an investigation into tax deals, the Financial Times reported citing people familiar with the matter.

Details of the probe, which may come out later this week, could leave the Cupertino-based company with billions of euros in fines, the FT reported.

The Irish government, in a statement in June, said it was confident that it has not breached state aid rules and will defend its position vigorously.

Apple could not be reached for comment outside regular business hours.

Preliminary investigations by the European Commission into Apple's tax deals in Ireland claim the company benefited from illicit state aid after striking illegal deals with Irish authorities, the FT reported, citing people involved in the case.

The European Commission, the European Union's competition authority, is also investigating corporate tax deals in the Netherlands, Luxembourg, as well as Ireland, following revelations about the tax-planning practices of major corporations such as Apple, Google <GOOGL.O> and Starbucks <SBUX.O>.

A U.S. Senate committee investigation revealed last year that Apple had cut billions from its tax bill by declaring companies registered in the Irish city of Cork as not tax resident in any country.

Ireland, the Netherlands and Luxembourg all have specially structured corporate tax arrangements, but so do other EU member states. In the majority of member states, the effective corporate tax rate is nearly always lower than the nominal rate, which is usually the result of "sweeteners" in the tax code.