Trade union GdF said on Wednesday that the 200 apron control staff will go on strike from 1400 GMT until 2100 GMT, having failed to reach a wage agreement with the airport's operator Fraport (FRAG.DE) in arbitration.

"We expect that we will create massive problems for Fraport," GdF board member Markus Siebers told journalists in Berlin.

Fraport, which has called a press conference scheduled for 1430 GMT, said it could not rule out delays and flight cancellations due to the strike.

GdF has said that apron controllers' pay no longer reflects the additional complexity resulting from the recent opening of a fourth runway at Frankfurt airport.

Fraport, meanwhile, said the strike announcement was "absolutely incomprehensible" and said GdF's demands were much too high for the company to shoulder.

The GdF union kept German air passengers on tenterhooks for months last year, when it was trying to push wage demands for air traffic controllers, repeatedly threatening to strike.

The employer, Germany's DFS air safety authority, fought the union in court and both sides finally reached a deal in October, averting a strike that would have disrupted thousands of flights across Europe.

(Reporting by Axel Hildebrand and Maria Sheahan; Editing by Erica Billingham)

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