Ryanair may have to drop many international routes following defeat in the French courts this week, chief executive Mr Michael O'Leary is quoted as saying in today's Financial Times.
The carrier is to suspend flights between Stansted and Strasbourg from September 24th because of a dispute with Groupe Air France over payments Ryanair receives to fly to secondary European airports.
"If we continue to have rulings against us, growth will be confined to privately owned airports so it would exclude development of low-cost routes in France. Pulling out would be one of the options," Mr O'Leary said.
He added the airline was ready to stop using Charleroi airport in Belgium if a European Commission finding - due in the autumn - goes against him.
"Strasbourg is nothing more than a skirmish. It would not have happened if it was not against the background of alleged state aid at Charleroi. Charleroi is our Waterloo," he said.
Aside from Strasbourg, the airline flies to 18 regional French airports from London including Biarritz, Montpellier and Perpignan. France represents three million of the company's 24 million passengers, contributing about 12 per cent of turnover.