BERLIN

Hundreds of flights were canceled at three German airports on Thursday as security staff began a 48-hour strike over an ongoing dispute over pay and work conditions.

The strike forced the Hamburg airport to cancel over 300 departures scheduled for Thursday and Friday, affecting around 40,000 passengers.

“Flight cancellations and delays are also to be expected on arrival,” the airport operator said in a statement and asked passengers to contact their airline for cancelations or rebooking.

Cologne/Bonn airport announced that more than 120 flights have been canceled today, and most of the 225 flights planned for Friday would have to be canceled.

Passengers were advised to check the current status of their flight with their airline or tour operator before traveling to the airport.

The strike also grounded dozens of flights at Dusseldorf airport and caused longer waiting times at security checkpoints in the morning hours.

The ver.di trade union has announced that security staff working at Stuttgart airport will also join the strike action on Friday.

The union, which represents thousands of workers in the aviation security sector, is demanding an increase in overtime pay, and surcharges for work on weekends, public holidays, and during night shifts.

The latest round of negotiations between the union and the Federal Association of Aviation Security Companies (BDLS) ended without an agreement last week.

A new round of negotiations is expected to take place on April 27 and 28.