Cabin crew on the plane said the suspect, a British man resident in Stockholm, had been attempting to secretly film security procedures on board a flight that left Stansted in London on Monday night.
Staff quickly alerted police to their suspicions of air traffic sabotage. Officers were in place to arrest the suspect on his arrival at Skavsta airport south of Stockholm at 1am.
The suspect was released at 11.30am but the suspicions against him remain, according to police in Nyköping.
“We’ll now have a look to see if he was just filming things that everybody already knows about, like locating emergency exits and putting on safety belts, or whether it was something else,” police investigator Svante Melin told The Local on Tuesday morning.
Police were unable to say if or when they were planning to make contact with the members of Ryanair staff who reported the incident.