All flights to and from Hamburg Airport have been cancelled in response to a pay strike after services trade union verdi brought the action forward by a day without prior notice, an airport spokeswoman announced on Sunday.

The airport in Germany’s second largest city said the one-day strike, called over pay and conditions, began earlier than expected “without any notice.”

More than half a million people are facing travel disruption at German airports on Monday where a 24-hour strike has led to thousands of flight cancellations in a dispute about workers’ pay.