Pilots and flight crew at German airline Lufthansa kicked off their preannounced all-day strike on Thursday in a dispute over pay and working conditions.

A spokesperson for the UFO union confirmed that the warning strike by cabin crew at Lufthansa and its regional subsidiary Lufthansa CityLine started at 12:01 a.m. local time.

The work stoppages are planned to last the entire day until midnight, meaning that hundreds of aircraft operated by Germany's largest airline are expected to remain grounded.

Lufthansa said it expected extensive flight cancellations but initially did not provide exact figures.

Departure boards at major airports such as Frankfurt and Berlin show only a very small number of Lufthansa flights still scheduled to operate. Passengers are being informed primarily through digital channels and are advised not to travel to the airport without checking their flight status.

Around 4,800 pilots at Lufthansa and its cargo subsidiary Lufthansa Cargo are striking in a dispute over higher company pensions. Cabin crew are staging the warning strike to force negotiations on several collective bargaining issues.

The UFO union has also called on staff at regional subsidiary Lufthansa CityLine, which is facing closure, to join the walkout. Management has rejected the unions' demands. Other group companies are not expected to be affected by the strike.