FRANKFURT - Thousands of passengers were left stranded at German airports on Tuesday as more than 60,000 ground staff and other public sector workers staged walkouts across the country to increase the pressure in a pay dispute.

Lufthansa had said it was canceling more than 800 of its planned 1,600 flights on Tuesday and Frankfurt airport operator Fraport had warned of disruption.

As well as Frankfurt, Germany's busiest hub for airlines, the strikes hit airports in Munich, Cologne and Bremen. The industrial action also affected nurseries, rubbish collection services and swimming pools in several German states.

German union Verdi wants a 6 percent pay rise for its 2.3 million public sector employees at the federal and local level. Germany's federal government and municipalities have rejected that, saying such a rise would force them to outsource jobs.

The union said more than 60,000 workers in eight German states took part in the strikes, and further walkouts were planned across the country in coming days.

Verdi said it was asking 15,000 employees at Deutsche Telekom to join the strikes on Wednesday, mostly in the services and technical sectors.

Some air passengers expressed frustration over the delays.

"I'm upset. I'm affected by these strikes too often," said Roswitha Karl, who was at Frankfurt airport waiting to board a flight to Moldova for a holiday.

"First, there was the pilots'strike, then the ground staff and then the security staff, it's a matter of luck," said Karl.

Airline rebooking counters had a long queue of passengers, while other stranded travelers were waiting in the terminal. While some frantically tried to change their reservations, others took the delays in their stride.

Jana Glaeser had arrived in Frankfurt from Miami and her flight to Berlin was canceled. "Now we're getting a train ticket instead. Hopefully everything works out," she said.