Parts of Frankfurt Airport were evacuated and dozens of flights cancelled after a French family of four got past security despite a positive test for explosives.
Thousands of passengers are crowded in Hall A in Terminal 1 of Frankfurt Airport due to a partial evacuation. Photo: AFP
Police blamed "an error by a security officer".
It led to boarding being halted and a partial evacuation of Terminal 1.
After the alarm had been raised, the family were located in the terminal, re-checked and allowed to continue on their journey after being cleared.
A police spokeswoman said one of them had not fully completed security checks.
Police did not clarify what had triggered the positive explosives test.
The police action came a week and a half after a security scare involving a person who passed through an unmanned checkpoint at Munich airport, Germany's second-biggest after Frankfurt. That triggered an alarm which caused the cancellation of 300 flights and affected more than 30,000 passengers.
Travellers at Frankfurt Airport - Germany's largest - are now facing cancellations and long queues to re-enter the departure area. More than 49 flights have been cancelled, German media report.
Passengers earlier complained of confusion and lack of information during and after the evacuation.
"If this continues, we will miss the next flight," a Belgian passenger told Frankfurter Allgemeine from the end of a security queue, after obtaining a ticket for a second flight.
Around 1500 flights were set to take off or land at Frankfurt airport.
The carrier has booked 2,000 hotel rooms for the night to accommodate affected passengers, it said.
German airliner Lufthansa, which has its main hub at the airport, said it was working on a new flight plan and would update passengers as soon as possible.
German police defended the evacuation on social media, saying they had to exclude any and every risk.
-Reuters / BBC