Turkish special forces seized a passenger who is suspected of making a bomb threat and trying to hijack a plane, demanding to go to the Winter Olympics venue of Sochi, CNN Turk and other Turkish media said on Friday.
Turkey scrambled an F-16 fighter jet to accompany the Pegasus Airlines plane as it landed at the airport after a flight from the Ukrainian city of Kharkov.
Some media reports said the suspect had been taken away for questioning but one official at the Sabiha Gokcen airport in Istanbul said the suspect had not yet been seized.
The passenger was believed to have drunk alcohol and was calmed down by the crew and persuaded to let the plane, a Boeing 737-800, land in Istanbul at 6:02 pm (1602 GMT), according to Dogan news agency.
An official from Turkey's transport ministry said there were 110 passengers on board and confirmed that a bomb threat had been made but said the plane had landed safely.
Security teams were continuing inspections on the plane, the ministry said in a statement.
"People are still inside but the pilot called security and gave them a signal that they can enter the plane. There is a translator - a Turkish man near the Ukrainian to calm him down," one airport official said.
Reporting by Orhan Coskun, Daren Butler and Evrim Ergin; Writing by Nick Tattersall; Editing by Dasha Afanasieva and Sonya Hepinstall