About 100 flights were cancelled to and from Frankfurt airport on Wednesday after a security scare, a spokesman for airport operator Fraport said.
Germany's largest airport reopened after parts of Terminal 1 were evacuated due to a "suspicious person" who passed into a secure area without undergoing a routine search.
A Lufthansa spokeswoman said that all its customers affected by the cancellations and delays had the option of exchanging their flights for a rail ticket where possible.
Federal police said that they had apprehended a female suspect and were now questioning her, without giving further details.
Police also confirmed that a special vehicle for bomb disposal had been deployed at the airport due to an abandoned piece of luggage, adding that the incident was unrelated to the female suspect.