A strike on Tuesday by security staff at eight German airports among them Frankfurt, a major intercontinental hub-led to widespread disruption and flight cancellations.

The ver. di union called the all-day strike Frankfurt, Germany’s busiest airport, as well as Berlin, Bremen, Hamburg, Hannover, Stuttgart, Duesseldorf, and Cologne-Bonn, before a round of pay talks with employers that are set for Thursday. It followed walkouts at several airports last week.

At Frankfurt, 108 out of the day’s 790 planned flights had been canceled by Tuesday morning, German agency DPA reported. Passengers due to start their journeys at the airport were unable to board, though passengers could transfer flights.

All 88 planned departures from Hamburg were canceled.

Security checks at German airports are under the supervision of federal police but are largely conducted by private firms. Security officials in Bavaria are paid in line with a pay deal for public service employees and aren’t striking.