German airline Lufthansa on Wednesday cancelled more than 20 more flights to and from Berlin, Frankfurt and Munich due to the knock-on effects of the previous day\'s strikes by cabin staff. \"The Independent Flight Attendants\' Organisation or UFO has ended the strikes at Berlin, Frankfurt and Munich airports. Flight operations from and to Berlin, Frankfurt and Munich are still affected,\" Lufthansa said in a statement posted on its website. It warned of \"unscheduled cancellations and delays of Lufthansa flights\", but said services operated by its regional subsidiaries, Air Dolomiti, Augsburg Airways, CityLine, Eurowings and Germanwings would not be affected. \"However, at this stage Lufthansa cannot say for sure what exact impact the strike action will have. Even after the end of the strike, we foresee irregularities in flight operations,\" it warned. The previous day, cabin crew staged eight-hour walkouts at Lufthansa\'s main hub in Frankfurt, as well as in Munich and Berlin, over pay and conditions, forcing the airline to ground more than half of its scheduled services -- 217 out of 370 in all. And if management tables no new offer, the UFO labour union has threatened to hit every German airport with a 24-hour strike on Friday. UFO is seeking a five percent pay increase for cabin staff backdated to January after three years of wage freezes. It is also opposed to the use of temporary cabin staff on Lufthansa aircraft. Lufthansa spokesman Klaus Walther said the airline had offered to hike salaries by about 3.5 percent and stop resorting to fixed-term contracts and temporary staff. The airline is already facing headwinds because of rising fuel prices and fierce competition. A 2009 strike by cabin crew cost Lufthansa tens of millions of euros. In February this year, Frankfurt airport\'s apron control staff -- traffic controllers who guide aircraft on the tarmac -- walked off the job over demands for higher pay.