Ryanair said the 50,000 customers affected by the cancellation of 600 flights over the two days were given alternative seats or offered full refunds. Labour unions in Portugal, Spain, Belgium and Italy claim that employees of Ryanair or its subsidiaries have reduced leave allowances and access to state benefits because they were hired under contracts governed by countries where they are not based.
In response, the Dublin-based airline published June salary slips on its website. It argued that pilots and cabin crew are fairly paid in Portugal, Spain and Belgium, the three countries where strikes initially were called for Wednesday and Thursday.
Chiara Luchi, a 21-year-old student who planned to fly back to Pisa, Italy with her father after a weeklong holiday in Madrid, said they found their flight was cancelled when they arrived at Madrid airport.
"I have sympathy for the workers, but I don't think this is fair for the customers and those who have to travel because they need to work," Luchi said as she stood in a line with dozens of other stranded passengers waiting to file complaints.
After some back and forth, Ryanair offered to pay to put the father and daughter on a flight to Rome with another airline. The two main unions representing pilots and cabin crews in Spain said negotiations with Ryanair over the contracts of more than 4,000 cabin crew members across Europe had failed.
Spain had the most planned cancellations ahead of the strike, with nearly one out of four daily Ryanair flights suspended. Spain's Ministry of Development said disruptions were minimal Wednesday, and the flight cancellations and delays that did take place were caused by walkouts by Italy-based crews.
Earlier, authorities required Ryanair to ensure that all flights serving the Spanish islands operated, and that at least 35 percent of domestic flights and 59 percent of international ones were to be unaffected.
In Italy, at least 165 flights were cancelled, according to the Italian civil aviation authority. Ryanair didn't immediately confirm the number, but said in a statement that cancellations were due to a "strike action by a small number of cabin crew in Italy."
Italian unions said they want a collective contract that recognizes workers' rights and alleged that Ryanair has refused to negotiate. A group of cabin crew workers wearing Ryanair uniforms gathered outside the departure terminal at Rome's Ciampino airport shouting "Ryanair must change." They had their faces covered, saying they feared retaliation from the airline.
At three Portuguese airports, 36 of 45 scheduled Ryanair flights were cancelled, and the airline's check-in areas were largely deserted. Ryanair had said before the strike that as many as 50 of 180 scheduled flights from and to Portugal could be cancelled during the strike period.
Bruno Fialho, of Portugal's Civil Aviation Cabin Crew Trade Union, urged the government to intervene in the dispute, claiming the airline is "trampling on Portuguese laws" by not respecting the labor rights of local staff.
The demands come as Irish pilots held rolling strikes that hit bookings and consumer confidence in Ireland, according to Ryanair. The airline responded Thursday by warning hundreds of pilots and cabin crew members that they could lose their jobs as it cuts its Dublin-based aircraft fleet from 30 to 24.
Ryanair operates a fleet of over 450 aircraft from 87 bases. __ Nicole Winfield in Rome, Danica Kirka in London and Barry Hatton in Lisbon, Portugal contributed to this report.