German authorities found no evidence that three British men, reported by fellow passengers on a London-bound plane to have been having a "suspicious conversation" about terrorism, posed any danger.
Passengers on easyJet flight EZY3246 on Saturday, travelling from Slovenia to England, complained to airline staff that the men were talking about "terrorist matters".
Mid-air, the plane was diverted and made an emergency landing in Germany's cologne.
The accused trio were detained.
"The criminal investigation against them has been halted. No evidence was found," a local police spokesman said on Sunday, announcing that the men were released without charge. "We now believe that there was never any real danger."
The unnamed men, who worked for a British company, are aged 31, 38 and 48.
It was not immediately clear when the men, who were returning to London after a business trip, would travel onto Stansted Airport as planned.
Passengers on Saturday's flight had claimed one of the men carried a book on which the word "kill" appeared with a sniper rifle on its cover, police and state prosecutors said in a statement.
Dozens of novels include the word kill in titles, and many feature guns on covers.
The German Bild newspaper said passengers told airline personnel they had heard the men using words including "bomb" and "explosive", and said one carried a suspicious backpack.
That backpack, belonging to the 48-year old, was examined and blown up in a controlled explosion.
Nothing dangerous was ultimately found to have been in the bag or on the aircraft.
The incident forced the diversion of 17 inbound flights, delays in 20 departing flights and cancellation of two flights, a spokeswoman for Cologne airport said, adding that air traffic had returned to normal after a three-hour interruption.
Nine people received medical treatment after all 151 passengers were evacuated from the Airbus 319 aircraft using emergency slides.
The remaining passengers had departed on another easyJet plane for London earlier on Sunday.
EasyJet said passengers received hotel vouchers and meals during their stay, and thanked them for their understanding.
"The safety of easyJet passengers and crew is our highest priority," the company said in a statement.
They said the alleged conversation could not be verified.
Seventeen other passengers and the easyJet crew were questioned about the incident at Cologne police headquarters, police said in a statement.
Several European countries are currently on high alert following a number of deadly attacks.
Amid this climate, several airlines in the United States and Europe have recently removed innocent passengers of Middle Eastern or Asian descent from planes on unfounded allegations by fellow passengers, leading to claims of racial discrimination.
In August 2016, easyJet forced British Muslim siblings out of a plane on the runway in London, where they were intrerrogated by armed police after passengers falsely claimed they were members of the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).