Ryanair Holdings Plc became the latest European airline to warn about mounting costs, saying labor strife and higher fuel prices are taking their toll.

Europe’s biggest discount carrier cut its full-year profit guidance by about 12 percent, to between 1.1 billion euros ($1.27 billion) and 1.2 billion euros, according to a statement Monday. Two days of strikes in September translated into lower traffic and fares, as well as fewer bookings in October as customers feared more walkouts, it said. Higher fuel prices also added to costs, signaled by rival EasyJet Plc last week.

Ryanair said it would trim its winter schedule by 1 percent, pulling four aircraft from a base at the Dutch city of Eindhoven, and two from Bremen, Germany. It will also cut back flights out of the German base of Niederrhein, the statement said.

The shares dropped as much as 12 percent in Dublin, the most in more than two years, while EasyJet shares fell as much as 6.3 percent.

Ryanair Chief Executive Officer Michael O’Leary, who has presided over years of rising profits and passenger growth, has grappled with a turbulent year and was already forecasting its first profit drop since 2014 this fiscal year. The company reversed its long-held policy of not recognizing unions, and while it notched a deal with Irish pilots in August, most other unions are holding out.

“While we successfully managed five strikes by 25 percent of our Irish pilots this summer, two recent coordinated strikes by cabin crew and pilots across five EU countries has affected passenger numbers,” O’Leary said in the statement. “Customer confidence, forward bookings and third quarter fares has been affected.”