A flight was diverted and a man was arrested following a report of a sexual offence on board a plane to Ibiza.
The Jet2 flight from Edinburgh to the Balearic Island was forced to land in Bristol after the incident on Tuesday morning.
Officers said a passenger received medical treatment after the flight landed in the Scottish capital.
Avon and Somerset Police said in a statement: "A Jet2 flight from Edinburgh to Ibiza was safely diverted to Bristol Airport.
“The crew raised concerns regarding a passenger, who received medical attention upon landing.
"Attending officers subsequently received information, prompting the arrest of a male passenger on suspicion of a sexual offence, who has been taken into custody.
“We can confirm this relates to an alleged incident onboard the aircraft. Enquiries into what happened are at an early stage and continue.”
The force added the man who was arrested has since been released on conditional bail.
A spokesperson for Jet2 said: “We can confirm that flight LS789 from Edinburgh to Ibiza diverted to Bristol Airport yesterday, so that police could offload a passenger following an incident onboard.
“As this is a police matter, we cannot comment any further at this stage.”
Every year tens of thousands of British tourists fly to Ibiza, which has a reputation for hedonism and hard partying, with clubbers from around the world flocking to the island every year to sample its night spots.
The Balearic Islands are among some of Spain’s most tourism-dependent regions, with the industry accounting for a large share of the country’s GDP.
Last year Jaume Bauza, the islands’ head of tourism, suggested holidaymakers who break strict rules could be ordered to go home.
Tourists who breach the rules could be blacklisted from notorious party hotspots such as Magaluf in Majorca, and the West End of San Antonio in Ibiza.
New laws were introduced in some parts of the Balearics in 2020 in a separate bid to clamp down on badly behaved tourists on booze-fuelled holidays.