An F-16 jet was scrambled on Friday to force down an Istanbul-bound airliner after a passenger tried to hijack the aircraft and order it to fly to Sochi, where the Winter Olympics opening ceremony was under way, Turkish officials said.

Turkish media reported that a Ukrainian man brandishing a detonator tried to gain access to the cockpit of the Pegasus Airlines flight while it was in the air.

He was overpowered by security forces when the Boeing 737-800 airliner landed at Istanbul's Sabiha Gokcen airport at 6:05pm (4:05pm GMT). He was taken to an undisclosed location for questioning.

"A Pegasus Airlines plane with 110 people on board had to land at Sabiha Gokcen airport because of a passenger who threatened passengers with a bomb," said Habib Soluk, deputy Turkish transport minister.

"We are sure that he didn't enter the cockpit. We know that the aircraft was hijacked before it entered Turkish airspace," he said.

The aircraft departed from Kharkov, Ukraine, for the scheduled flight south over the Black Sea to Sabiha Gokcen. The hijacker wanted to divert it east to Sochi, the Russian city on the Black Sea coast.

Attempted to reach cockpit

When the man tried unsuccessfully to get in the cockpit, the pilot emitted a hijack alert and the Turkish F-16 military jet was scrambled.

The plane was immediately stormed by Turkish anti-terrorism commandos after it landed and the man was seized, reports said.

Turkish officials have yet to confirm whether any explosives were found on board.

Turkish television channels showed images of the aircraft surrounded by ambulances, fire engines and police vehicles with flashing lights.

They showed a still image of the would-be hijacker, in his 30s or 40s, with short hair and wearing what looked like a red, white and blue ice hockey shirt with the number 11.

"I received confirmation that everyone on board is okay and that the plane is fine. I know the pilot... he is experienced and I am sure everything is fine," the head of Turkey's main pilots' union, Gurcan Manti, told the NTV television channel.

High security in Sochi

The incident happened just as the opening ceremony for the $50 billion Sochi Olympic Games got under way, with 40 heads of state and leaders including UN Secretary General Ban Ki-moon and Chinese President Xi Jinping attending.

Security concerns were already heightened after the United States announced a temporary ban on liquids and gels in hand luggage on Russia-bound flights, following a warning that militants could stuff explosives into toothpaste tubes.

Russia last month banned domestic travelers from having any liquids and gels, including toothpaste, in their carry-on luggage ahead of the Games, which run until February 23.

Russian President Vladimir Putin is under huge pressure over the Games after an Olympic build-up dogged by controversies over gay rights and construction delays.

Concerns over militant attacks skyrocketed after two suicide attacks killed 34 in the southern Russian city of Volgograd in December. They were blamed on extremist militants from the Northern Caucasus region.

Threat from insurgents

Russian security forces are still fighting insurgents in the area, which is close to Sochi, and militants have threatened to strike targets in Russia during the sports event.

About 40,000 members of the Russian security forces are on duty in and around Sochi in one of the tightest operations ever mounted at an Olympics.

Two US warships have deployed to the Black Sea, ready to offer assistance in the case of a security emergency necessitating the evacuation of Americans.

US President Barack Obama said earlier Russia had an "enormous stake" in thwarting "terrorism" at the Games, adding that Washington was doing everything it could to help keep athletes safe.

"I think the Russians have an enormous stake, obviously, in preventing any kind of terrorist act or violence at these venues. They have put a lot of resources into it," US President Barack Obama said in an interview with US television station NBC.

(FRANCE 24 with AFP)