German airline Lufthansa has sought a court order to halt a crippling week-long strike by cabin staff, as the trade union said it would expand its industrial action to include all flights.
Amid a protracted dispute over savings to help it fight low-cost rivals, the German flag carrier on Tuesday filed motions with two courts for temporary injunctions against the work stoppages which began last Friday and are scheduled to continue until this Friday.
A Lufthansa spokesman said it was basing its case on demands by the UFO flight attendants' union being "too vague" and unjustified under German labour law.
The head of UFO, Nicoley Baublies, hit back, telling reporters that the union would now strike on all short-, medium- and long-haul flights from Wednesday until Friday.
He called for immediate talks and warned that the union could still decide to extend strikes beyond Friday.
"As soon as Lufthansa joins arbitration with us without preconditions, we will end the strike," Baublies told reporters.
"From one minute to the next."
If allowed to continue, the industrial action would become the longest in Lufthansa's history.
The district court in the western city of Darmstadt said it would hear the case Tuesday evening and announce a ruling, news agency DPA reported. It was not immediately clear when the other court, in Duesseldorf, would decide on the motion.
Lufthansa scrapped 929 flights on Monday, grounding 113,000 passengers. On Tuesday, 136 flights were axed, affecting 27,300 passengers.
The airline presented a new offer to the union late on Monday, with improved bonuses and retirement provisions, but UFO called it unacceptable.
The dispute over pay and early retirement provisions dates back to December 2013, when the company decided to embark on cost cuts in the face of intense competition from no-frills carriers.
The union is demanding that the current system of early retirement provisions remain unchanged, but Lufthansa has argued that those measures are too expensive.