Police said it was unclear whether the person who entered the secure area did so intentionally
A security scare at one of Europe's busiest airports is causing travel disruption across the continent.
Parts of Frankfurt airport's Terminal 1 were evacuated after a passenger entered the airside area without fully completing a security check, the hub's operator said.
"The federal police therefore cleared Piers A and A+ and passengers will undergo the security check again," Fraport told Reuters.
German police said it was unclear whether the person who entered the secure area did so intentionally and whether they were carrying any forbidden items.
A spokeswoman for Fraport said the breach would lead to flight delays at the airport, German airline Lufthansa's main base.
Passengers took to social media to express their frustration at the delays.
Esports commentator James Carrol tweeted: "Departure terminal Z completely shut down at Frankfurt Airport. Im gonna have a huge delay :'( Seems like a security reason."
Frankfurt is Europe's third busiest airport in terms of passenger numbers, behind Charles de Gaulle in Paris and Heathrow in London.