The union, UFO, made the announcement on its website. It had earlier said on Thursday it would deliberately delay giving precise details on the strike until six hours before it was to begin, in deference to passengers.

"If Lufthansa were to know concrete details more in advance, they would make additional efforts to shift staff and aircraft to other airports," UFO labor union boss Nicoley Baublies told the news agency DPA.

Negotiations broke down

On Tuesday, UFO called for the walk-out after overnight negotiations with management about wages and staff policy had failed. The union was seeking a five percent pay increase for cabin staff, as well as assurances from Lufthansa to stop the use of lower-paid temporary workers in cabin crews.

Baublies reaffirmed the union's determination to launch an open-ended strike, but expressed the hope that pin-pointed actions might force Lufthansa to make a new offer.

"If that isn't going to happen, we have drafted plans for an all-out and indefinite strike," he told DPA.

Extended industrial action could prove costly for Lufthansa, which already faces strong headwinds from rising fuel prices and fierce competition from low-cost carriers, which resulted in an a loss of 20 billion euros ($25.1 billion) in the first six months of this year.

Nevertheless, a spokesman for the airline told reporters in Frankfurt on Thursday that management had worked out contingency plans aimed at "bolstering" the affects of the strike for passengers "as best as possible."

uhe,jr/mz (dpa, Reuters)