Frankfurt airport could be set for major disruption next week, with security personnel scheduled to strike on Tuesday January 15.

Members of the Verdi trade union are taking the action over an ongoing pay dispute, with staff set to walk out between 0200 and 2000 local time.

Lufthansa warned that “a considerable amount of disruptions are to be expected regarding flight operations to and from Frankfurt Airport”, and said that customers with flights scheduled to depart Frankfurt may change their ticket free of charge to any date between January 11 and 20.

The carrier said that it would publish flight cancellations on Sunday afternoon, at which point online rebooking will also be possible.

In a post on its official Twitter page, Frankfurt airport said that “Due to a strike by security personnel there will be significant disruption at Frankfurt Airport on 15.01. Security checks outside the transit area will not be staffed until 8pm and passengers will not be able to reach flights during the strike period.”

Lufthansa is advising customers not to travel to the airport during the strike period, but stresses that this does not apply to transit passengers changing flights at Frankfurt.

“Although all aviation partners agreed that we want to improve the situation for our passengers in 2019, the Verdi union is escalating this collective bargaining dispute disproportionately and to an unacceptable extent,” said Dr. Detlef Kayser, Member of the Executive Board of Deutsche Lufthansa AG for Airline Resources and Operations Standards.

“This series of strikes can certainly no longer be described as warning strikes. It is also clear that Verdi has no interest in making its contribution to improving Germany as an aviation location. We already have the lowest quality security checks at the highest costs, compared to Europe and other countries around the world.”

Members of the Verdi union have already staged industrial action at Cologne Bonn, Dusseldorf and Stuttgart airports this week.,