Cabin crew and German flag-carrier Lufthansa have confirmed they will strike again on Tuesday as a dispute over pay and conditions rumbles on.
Services at Frankfurt were disrupted on Friday when members of the UFO union walked out as part of eight hours of industrial action.
UFO has confirmed it will call workers out for longer tomorrow, at more airports, but exact details have not been confirmed to ensure Lufthansa is unable to call up replacement crews.
Union official, however, said it will warn at least six hours before new stoppages begin.
UFO has been calling for a five per cent pay increase for workers after two years of stagnant wages.
Lufthansa in return has offered 3.5 per cent in exchange for longer working hours.