The flight, which was due to leave Zaventem airport in Brussels at 7am this morning, was delayed for several hours after the plane was evacuated because of the scare.
Police told the VTM NIEUWS channel that the men were getting on board the Ryanair flight 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'."
Ryanair told the Standard it had requested police assistance after a number of passengers became disruptive prior to the plane’s departure.
The plane was eventually allowed to leave at 9.25am after all the luggage was removed and checked. The bomb squad attended accompanied by sniffer dogs.
Police detained the men who could face prosecution as it is an offence to cause a false bomb scare.
Officers said the joke was not appreciated by the airline or passengers who were extremely alarmed by the incident.
A full investigation is being carried out and a preliminary report has been sent to the local prosecutor’s office, according to VTM NIEUWS.
A Ryanair spokesman said: “The crew of this flight from Brussels to Madrid 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."