FRANKFURT (Reuters) - Frankfurt airport operator Fraport (>> Fraport) plans to invest around 150-200 million euros ($171-$228 million) in a new pier for low-cost carriers, its chief executive Stefan Schulte said on Thursday.

Fraport is seeking to expand low-cost flights from Frankfurt in order to make up for waning growth from traditional airlines, such as its main customer Lufthansa (>> Deutsche Lufthansa).

Fraport, which has signed up Ryanair (>> Ryanair Holdings plc) and Wizz Air (>> Wizz Air Holdings PLC) as new low-cost customers, had said in May it was planning a new pier for low-cost flights that would be part of a new Terminal 3 but would open before the rest of the terminal.

Schulte told an event in Frankfurt the pier would be operational in 2020. Terminal 3 is due to open in 2023.

Schulte had earlier told German paper Die Welt that he expected passenger numbers in Frankfurt to rise to around 64 million this year.

That would be around 5 percent growth on last year's 60.8 million and above Fraport's previous forecast that it would reach the upper end of a 2-4 percent range.

(Reporting by Peter Maushagen; Writing by Victoria Bryan; Editing by Mark Potter)