A pilots strike grounded more than half of Lufthansa's lucrative long-haul flights on Thursday, the latest action to pressure management in a protracted row over early retirement benefits and cost cuts.

Lufthansa is trying to cut costs to levels nearer those of its rivals as it is squeezed by budget carriers Ryanair and easyJet on European routes and airlines such as Turkish and Emirates on long-haul flights.

Including Thursday's strike, the second of three planned for this week, pilots have walked out 13 times since April affecting almost 1 million passengers. Other Lufthansa employees are starting to worry the row could damage the business for good.