The European Commission (EC) will accuse Apple of benefiting from illicit state aid in Ireland, based on findings of an investigation into tax deals. The probe, which may come out later this week, could leave the Cupertino-based company with billions of euros in fines.

The Irish government, in a statement in June, said it was confident that it has not breached state aid rules.

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.

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 and Starbucks.

The European Commission will publish on Tuesday its reasons for opening the inquiry, a Commission spokesman said.

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.