Air traffic controllers in Italy have gone on strike, which is leading to some disruptions for travelers to Europe this week.

The air traffic controllers stopped work between 1 p.m. and 5 p.m., local time, on Friday, June 8 – the busiest part of the week for flights, the Independent reported.

Marseille Provence International Airport and airports on the island of Corsica are being particularly affected by the strike, as well as airports in Italy and in the U.K.

U.K. budget airline easyJet has already canceled several flights to Italian airports from Gatwick, and said in a statement that “Like all airlines, our flights to and from France, as well as those flying in French airspace, could be affected.” British Airways has also grounded two of its flights to and from Italy.

Irish airline Ryanair has also grounded at least six U.K.-Italy routes for the time being, noting, “As a result of this unjustified strike action, we also expect delays to flights to/from/over Italy and we advise customers due to travel on Friday to check the status of their flight.”

Italian airline Alitalia has been the worst affected by the strike, with more than 100 cancellations, according to the Independent.

More strikes will continue every five days through the month of June and Italian air traffic controllers are planning another strike on July 5. Controllers in France, at the Marseille Area Control Centre, will be staging a walk out on Saturday and Sunday, June 9 and 10. Meanwhile, rail workers in France have also been on strike this week, leading to even more travel disruptions.