The regulator said that similar investigations had been opened in July against Italian carrier Alitalia [CAITLA.UL] and Volotea and that complaints from customers on the issue were rising.

The watchdog said the cancelled flights were not during periods in which governments had imposed limits on movement between countries and that refunds of the tickets - an option envisaged by European rules - had not been offered.

(Reporting by Elvira Pollina and Giulia Segreti. Editing by Jane Merriman)