A four-day strike called by unions representing pilots for French carrier Air France was severely disrupting domestic and international flights on Friday, according to dpa. Air France said at least 40 per cent of scheduled long-haul flights and half of its short- and medium-distance flights would be cancelled. The company warned that last-minute flight cancellations were also possible. The job action was called to protest the increase of the retirement age for pilots from 60 to 65, and is to last until midnight on Monday. On Thursday, in an open letter to the pilots, company head Jean-Cyril Spinetta said the job action would cost the company up to 100 million euros (125 million dollars). Air France has set up a special hotline telephone number for passengers wanting information about a flight scheduled for the strike period. Outside of France, the number is 00331 5702 1055.