German travellers face fresh upheaval on Tuesday when security staff at Frankfurt airport, the nation's largest, are set to walk off the job in a battle for better pay that has already caused hundreds of flight cancellations.
Germany's powerful Verdi union announced on Friday that the Frankfurt strike would start at 2:00 am (0100 GMT) and end at 8:00 pm (1900 GMT).
It marks another escalation in their standoff with employers after walkouts by security personnel at airports in Berlin, Cologne-Bonn, Duesseldorf and Stuttgart this week led to more than 800 flights being scrapped, affecting over 100,000 passengers.
The scale of Tuesday's strike was not immediately clear.
"We can't rule out that other airports won't join the warning strike," Verdi warned.
The union, which represents some 23,000 aviation security workers across Germany, is pushing for a pay increase to 20 euros ($23.08) per hour.
Wages currently vary nationwide, with workers in some airports in eastern Germany earning around 14 euros hourly, compared with just over 17 euros for their peers in the capital and western parts of the country.
Employers' association BDLS meanwhile is offering increases of between two and 6.4 percent.
The next round of negotiations will take place on January 23.
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