EU antitrust regulators are investigating whether marketing support and airport charges deals between Ryanair and operators at France's Carcassonne airport gave the Irish low-cost carrier an unfair advantage in breach of EU rules.

The European Commission opened an investigation into the issue on Wednesday, saying it would check to see if a private investor would have been able to contract such deals.

The Commission has concerns that such arrangements could give the airline, sole commercial user of the airport, an undue economic advantage that its competitors do not enjoy, the European Union watchdog said in a statement.

Located in the south of France, Carcassonne airport is owned by Languedoc-Roussillon region and was operated by the local Chamber of Commerce (CoC) until May 2011 when Veolia Transport took over the operations.

The Commission said it was also investigating subsidies granted to CoC between 2000 and 2010 and other support to see if this had breached EU state aid rules.

The Commission has in recent months opened investigations into various arrangements between Ryanair and airports in Germany and Austria.

It is also scrutinising similar deals between airport operators and other budget airlines across the 27-country European Union.

(Reporting by Foo Yun Chee; Editing by Justyna Pawlak)