The flight, which had been due to leave Zaventem airport in Brussels at 7am this morning, was delayed for several hours with all the passengers being ordered to get off after the scare.
Police have confirmed the incident to the local news channel VTM NIEUWS which says the nine men were all of Belgian nationality.
They were getting on board the Ryanair plane to head for Madrid when one of them was heard shouting “Allahu Akbar” and indicating there was a bomb on board.
Peter De Waele of the federal police told the news channel: “The flight commander refused to take these nine people. One of them was a foolish joker and called ‘Allahu Akbar’.”
All the luggage had to be taken off as the bomb squad was called in with sniffer dogs.
Nothing was found and the plane was eventually allowed to leave at 9.25am.
The “joke”, said the police, had not been appreciated by either the airline or the passengers, many of whom had been extremely worried by the threat.
One of the men at least will face prosecution as it is an offence to cause a false bomb scare.
A full investigation is underway and a preliminary report has already been sent to the local prosecutor’s office.
In March 2016, both the Brussels-Zaventem airport and the city’s metro were the subject of separate terrorist attacks that killed 32 people.
A Ryanair spokesperson said: “The crew of this flight from Brussels to Madrid (2 Sep) requested police assistance after a number of passengers became disruptive prior to departure.
“Police removed and detained the individuals before the aircraft departed to Madrid.
“We will not tolerate unruly or disruptive behaviour at any time and the safety and comfort of our customers, crew and aircraft is our number one priority.
“This is now a matter for local police.”