Ryanair will challenge a finding by the European Commission that it benefited from illegal state aid from two regional airports in Germany.
The commission has ordered the Irish airline to refund more than €800,000 in payments, which it said were in breach of EU competition rules.
Ryanair and Airport Marketing Services, its marketing subsidiary, are taking two similar but separate cases to the European Court of Justice (ECJ) over payments it received from airports in Zweibrücken and Leipzig–Altenburg.
In 2014, after a long investigation, the European Commission concluded that airport services and marketing agreements between Zweibrücken airport, in southwestern Germany, and a number of airlines including Ryanair were incompatible with state aid rules.
It found that Zweibrücken had duplicated existing services as it was located