German trade union Verdi called for all-day warning strikes on Thursday and Friday for workers in some areas of Düsseldorf, Hamburg and Cologne/Bonn airports. 

"The strike starts at midnight on Wednesday to Thursday and ends at midnight on Friday to Saturday," Verdi said on Tuesday. 

"Sectors to be affected include the aviation security area, passenger screening, personnel and cargo screening and handling. Longer waiting times or even flight cancellations may occur due to the strike," the union warned. 

Hamburg Airport said all departures would be canceled or run without passengers on Thursday and Friday due to a strike, some 80,000 passengers could be affected. Arrivals will still be possible, he added. 

Why did Verdi call for strikes? 

The reason for the strikes are the negotiations between Verdi and the Federal Association of Aviation Security Companies (BDLS) about the bonuses for night shifts, Saturdays, Sundays and work on public holidays. 

Workers are also fighting for a better collective agreement on overtime pay for security and service personnel at commercial airports. 

Despite recent strikes, there has been no progress so far. Millions affected by Germany's biggest strike in decades.

Meanwhile, German media reported that further warning strikes were also planned at Deutsche Bahn and other rail companies in the coming days. An exact date is not yet known, but according to media reports there has been talk of a strike this Friday. 

The rail and transport union (EVG) wants to announce this Wednesday how it will proceed in the pay dispute with Deutsche Bahn and around 50 other companies. 

In late March, the union, along with service union Verdi, called for a major nationwide strike, affecting airports and ports in addition to buses and trains.