A note found in one of the plane's toilets claiming that explosives were on board forced the flight from Krakow to Dublin to divert to Stansted Airport on Monday night.
A pair of Typhoon jets were sent from RAF Coningsby in Lincolnshire to intercept the plane after the captain alerted UK authorities, the Ministry of Defence confirmed.
“The captain followed procedure by alerting the UK authorities and diverted to the nearest airport (Stansted) where the plane landed normally, but was taxied to a remote stand where passengers disembarked safely,” a spokesperson for Ryanair said.
Essex Police said the plane was diverted on Monday due to “reports of a security alert” but nothing suspicious was found on board after investigations.
Two men, both of whom were onboard, have been taken into custody, police said.
A spokesperson for the force said: “A flight from Krakow to Dublin was diverted to Stansted Airport at around 6.40pm on Monday 13 July due to reports of a security alert.
”Following investigations on the plane, we have been able to establish there is nothing suspicious on board.
“The aircraft has been handed back to Stansted Airport and the operator.
”Two men - aged 47 and 26 - have been arrested on suspicion of making threats to endanger an aircraft and are currently in custody.”
Passengers disembarked safely at Stansted and a spokesperson for Ryanair on Monday night said they were “being checked by the UK police who will decide when they may travel onwards to Dublin on a spare aircraft”.
“Ryanair apologises sincerely for the delay and inconvenience caused to those affected by this diversion,” the airline said in a statement.
Additional reporting by Press Association