A union representing Lufthansa flight attendants has called members at Frankfurt and Berlin's Tegel airport out on strike as it escalates a dispute with Germany's biggest airline over pay and conditions.
The UFO union called on Berlin-based members to walk out for eight hours starting at 5am (4am UK time), and urged their counterparts at Frankfurt, Germany's busiest airport, to follow suit at 6am (5am UK time).
UFO also plans to hit Germany's second-biggest airport, Munich, on Tuesday. An 11-hour walkout there was set to start at 1pm (noon UK time).
The union opened its strike campaign with an eight-hour walkout in Frankfurt last Friday and warned of more to come if Lufthansa did not give ground.
Lufthansa said the walkouts would force it to cancel "a majority of flights".
Lufthansa listed around 200 cancelled flights this morning, most of them to and from Frankfurt - mostly on short-haul and medium-haul routes. These included flights to and from destinations including Los Angeles, Houston, Chicago, Beijing and Mexico City.
The union has given only a few hours' notice of where and when it plans to strike.
UFO is seeking a 5% pay rise for the airline's 18,000 cabin crew workers. Lufthansa has said it is offering a 3.5% raise.
Other issues in the dispute include the possibility of Lufthansa transferring flight attendants to its partner budget airlines with cheaper contracts as part of a cost-saving programme.
Lufthansa is trying to cut costs amid tough competition from budget carriers in Europe and from rising Gulf airlines.