German airline Lufthansa has been forced to cancel 50 long-haul flights to and from Frankfurt after its pilots called a strike in a dispute over their early retirement scheme. The strike was scheduled to run between 0600 and 2100 GMT on Tuesday but its knock-on effects meant that flights via Frankfurt, Europe's third largest airport, will be disrupted between late Monday and early on Wednesday. The Vereinigung Cockpit (VC) trade union, representing about 5,400 Lufthansa pilots, wants the airline to maintain a scheme that allows pilots to retire early at the age of 55 and still receive up to 60 percent of their pay before regular pension payments start. The strike at Lufthansa is the fifth by the airline's pilots this year. It follows a two-week stoppage by Air France pilots that cost the Franco-Dutch company 280 million euros ($355 million) before it ended on Sunday. The long-established European carriers are running into opposition from powerful unions as they try to cut costs to compete with budget airlines. Lufthansa has offered to keep the pension scheme for employees who started before this year but wants to increase the earliest possible retirement age for new recruits. The union says it is unfair for new pilots to not receive this option. The airline says the pilots have also failed to enter talks on how to reduce costs on routes to Asia, where Lufthansa is facing stiff competition from rivals like Emirates and Turkish. Germany's flagship carrier has agreed deals with cabin crew, catering and maintenance staff on getting costs down on the routes, and says the pilots must be prepared to talk. "The continuing strikes by Vereinigung Cockpit cause damage with unforeseeable consequences for all 120,000 employees, including the pilots," Lufthansa said in a statement. (Reuters)