The airport in Hamburg, Germany’s second largest city, said it had canceled all flights on Sunday because of a one-day strike over pay by ground staff called by a labor union that started its action earlier than expected without warning.

The airport had been expected to carry more than 40,000 passengers on Sunday, with 144 arrival flights and 139 departures, but only 10 flights took place before the strike took hold at 6.30 a.m. local time, Hamburg Airport said in a statement, which directed stranded passengers to contact their airlines. The airport said the strike, called by the labor union Verdi, had begun “without any notice” during a busy holiday.

“The union is paralyzing the airport and without notice right at the beginning of Hamburg’s spring break,” Katja Bromm, head of communications at the airport, said in a statement. The airport mainly serves European destinations.

The union, which represents public-sector service workers, did not immediately respond to a request for comment.

The strike had been planned to start at the airport on Sunday evening and continue through Monday. Strikes are also planned at around a dozen German airports for Monday, including the country’s busiest airports, Frankfurt, Munich and Berlin Brandenburg.

Around 510,000 people will be affected by the strike on Monday, with more than 3,400 flights canceled, according to A.D.V., the association of Germany’s airport operators, German news media reported. The latest strike represents an escalation after Verdi staged walkouts in February.

In a statement on Saturday, Verdi said that its strikes aimed to increase pressure on employers over stalled collective bargaining talks to improve conditions for more than 25,000 employees in the aviation security sector. Among the union’s demands are 30 days of vacation, additional vacation for shift work and an increase in the annual bonus, the statement said.

The strikes come amid what is effectively an economic crisis in Germany, traditionally Europe’s powerhouse. The country’s economy shrank slightly last year and it has recovered less well from the pandemic than most of its European peers and the United States.

The centrist conservative party, the Christian Democrats, secured the most votes in a parliamentary election last month in a rebuke to the country’s left-leaning government for its handling of the economy and immigration.