German authorities are questioning three British men detained after their conversations on board an easyJet flight from Slovenia to London prompted the pilot to divert to Cologne, Germany, a local police spokesman said.
No explosives were found in their luggage or on the plane and a spokeswoman for the airport said the remaining passengers were scheduled to fly on to London around 1100 GMT.
Nine people received medical treatment after all 151 passengers were evacuated from the Airbus 319 aircraft using emergency slides.
The pilot diverted the flight from Ljubljana to Cologne on Saturday evening after passengers reported that the men were talking about “terrorist matters”, police and state prosecutors said in a joint statement.
Bild newspaper quoted a spokesman for the German federal police as saying the pilot decided to land the aircraft in Cologne after passengers told airline personnel they had heard the men using words including “bomb” and “explosive”.
The men were aged 31, 38 and 48, a spokesman for Cologne police said.
Bild newspaper said the men worked for a London company and were returning to London after a business trip.
A backpack that belonged to the men was examined and destroyed in a controlled explosion by authorities but no dangerous contents or explosives were found in the bag or on board the aircraft, a police spokesman said.
Police and prosecutors had said they were investigating a suspicion that the men were preparing to carry out, “a serious violent crime that could have jeopardised the state”.
On Sunday, the police spokesman said it was unclear if any charges would be brought against the men.
The airport spokeswoman said air traffic had returned to normal after a three-hour interruption on Saturday evening. Seventeen arriving flights were diverted to other airports, 20 departing flights were significantly delayed and two flights were cancelled, the airport said.
No additional passengers were detained, the police spokesman said.