Ryanair announced on Wednesday that it had emailed and texted passengers on 400 flights to and from Spain that will be cancelled next Wednesday, 25 July, and Thursday, 26 July.
Airline cabin crews' unions in Belgium, Portugal and Spain are to strike over pay and working conditions forcing the low-cost airline to cancel 200 flights, out of the 830 a day it was due to run, from Spain on each of the two days.
Across Europe, the strikes will affect 50,000 of the 430,00 passengers carried by Ryanair.
The airline hasn't given specific details of any cancellations from Malaga-Costa del Sol, explaining only that any passengers affected had already been informed. If a message hadn't been received, it said, then people should go to the airport as normal as the flight will be running.
Ryanair has denied that working conditions for its crews in Spain, Belgium and Portugal are bad and has said it has done all it can to avoid the strikes. Kenny Jacobs, the company's marketing chief, said that the protests wouldn't achieve anything "other than disrupt family holidays and benefit other airlines".
Workers' unions, USO and Sitcpla, have disputed Ryanair's claims. "They have working conditions and business practices that are totally contrary to workers' rights as recognised in Spain," they claimed.
In December last year Ryanair announced that it would be recognising trade unions and so far, according to the company, some 60 per cent of its crews are covered by union agreements. Deals have been reached with unions to accept membership in the UK, Italy and most recently in Germany.
The company says that Ryanair cabin crew earn up to 40,000 euros a year and enjoy all legal benefits and extra perks, data that is disputed by the unions in Spain.