Lufthansa and union representatives on Friday agreed to begin a formal mediation procedure set for next Wednesday, after the airline offered permanent contracts to some temporary cabin crew.

If talks are abandoned, the cabin crew staff can go on strike "every four days, or fortnight or every three weeks," union head Nicoley Baublies told Focus, according to an advance excerpt of its Monday edition.

The union has 20 years worth of membership fees to fall back on to fund industrial action, Baublies told the magazine.

Previous talks broke down and strikes forced Lufthansa to cancel over 1,000 flights, after 13 months of negotiations over pay and working conditions.

Lufthansa has been resisting the union's demand for 5 percent pay increases and guarantees against outsourcing as it tries to slash costs in a plan to improve annual earnings by 1.5 billion euros ($1.9 billion) by 2014.