Germany's main carrier Lufthansa is to end direct flights to Sudan because of economic reasons, media reports say.

According to a document by the company, the airline’s direct flights between the German financial capital of Frankfurt and the Sudanese capital of Khartoum are expected to be suspended on January 19, AFP reported on Sunday.

"Lufthansa offers its customers an extensive worldwide network and regularly monitors its profitability. In this context it was decided to suspend services from Frankfurt to Khartoum,” stated the letter to clients, which dated back to October 22 and was signed by Lufthansa's Sudan general manager Hartmut Volz.

An industry source said the move will end the airline’s 51 years of service to Sudan.

Dutch airline KLM also ended its direct flights between Netherlands' capital, Amsterdam, and Khartoum, on March 31 because of rising costs.

In recent months, the cabin crew working for the Lufthansa held a series of strikes in Frankfurt and Berlin in a row with the airline's management over payments and other issues, forcing the cancellation of many flights and leaving thousands of passengers stranded.

Lufthansa is Europe’s largest airline in terms of overall passengers carried and fleet size.