All Ryanair flights to and from Frankfurt, Germany's busiest airport, from March 31 have been cancelled, it said.

Pilots and crew based at Frankfurt were informed on Friday and will be able to apply for jobs elsewhere in the Ryanair network, it added.

The carrier said it was still investing in its German operations, including a $200 million investment in a new base in Nuremberg with two aircraft.

Frankfurt airport operator Fraport said it had introduced an "extremely moderate" increase in fees.

"Many partners see it as fair. Everyone is treated equally, there are no special rights," a spokesperson for Fraport said.

(Reporting by Maria Sheahan and Matthias Inverardi; editing by Jason Neely)