German airline Lufthansa is cancelling more than 1,000 flights in and out of its Frankfurt and Munich hubs in the coming days due to a strike by ground staff on Wednesday.
Some 144,000 passengers will be affected by the cancellations between Tuesday and Friday, the carrier said.
Nearly 7,500 passengers had already been impacted due the cancellation on Tuesday of 47 flights, many of them long haul, that had been due to arrive in Germany on Wednesday.
Flights from Bangkok, Singapore, Boston, Denver, New York, Chicago, Los Angeles, San Francisco and Seoul to Munich were affected, as were connections from Buenos Aires, Johannesburg, Miami and New Delhi to Frankfurt, for example.
According to the company, the nationwide strike by ground staff will force 678 flights in Frankfurt and 345 flights in Munich to be scrapped, plus more elsewhere.
Many passengers could not be rebooked because planes are already packed on the following days. Lufthansa said the impact to operations would last days.
Verdi, one of Germany's largest unions, has called on the approximately 20,000 ground staff employed by Lufthansa to stage a one-day strike on Wednesday to build up pressure in the ongoing pay negotiations.
Lufthansa chief human resources officer Michael Niggemann criticized the move. "The early escalation after only two days of negotiations in a collective bargaining round that has so far been constructive is causing enormous damage," he said.
"It affects our passengers during the peak travel season, and it puts an additional heavy burden on our employees in an already difficult phase of air traffic."
In addition to the hubs in Frankfurt and Munich, flights to and from Düsseldorf, Hamburg, Berlin, Bremen, Hanover, Stuttgart and Cologne were also affected.
Passengers without the possibility to reschedule should not come to the airports because "few or no" service counters will be open, the company warned.
Verdi said it expected a high level of participation in the strike on Wednesday.
Verdi strike leader Marvin Raschinsky said he also expected effects on other airlines, as the individuals on strike also provide services to other companies.
Lufthansa has been forced to scrap thousands of flights to and from its national hubs Frankfurt and Munich this summer due to severe staff shortages.
