A 24-hour strike at seven German airports, including Frankfurt and Munich, was set to affect nearly 300,000 passengers on Friday, as unionised workers pressed for higher wages and threatened a summer of “chaos” if their demands were not met.

The strike coincided with the start of the Munich Security Conference, with more than 40 heads of state and 60 ministers expected to attend. In an early sign of the disruption, Romania’s foreign minister, unable to board a cancelled flight, will be forced to fly to Austria and then make the more than four-hour drive to Munich, a Romanian embassy official said.

It is the latest in a series of strikes and protests that have hit major European economies, including France, Britain and Spain, as higher food and energy prices knocked incomes and living standards following the pandemic and the war in Ukraine.

Around 295,000 passengers are affected by the cancellation of some 2,340 flights at Bremen, Dortmund, Frankfurt, Hamburg, Hanover, Munich and Stuttgart airports, according to the ADV airports association.

“We really haven’t had such an escalation through strike action,” ADV’s Ralph Beisel told broadcaster Bayerischer Rundfunk. “When we look at the airport terminals this morning, it reminds us more of the worst days of the coronavirus and less of a warning strike.” German trade union Verdi announced the strike on Wednesday.