A man was escorted by auxiliary police off a Scoot flight from Athens to Singapore early Monday morning after he refused to comply with instructions to leave an emergency exit-row seat.

A passenger who witnessed the incident told The Straits Times that the man, who looked to be in his early 60s, moved to the seat one hour before the landing time of 3.35am.

He refused to move from it even after flight attendants repeatedly asked him to do so.

Although Flight TR713 landed safely and on time, passengers had to remain in their seats for about 15 minutes as the man initially refused to leave with the auxiliary police.

In response to queries, Scoot said the man, who was on board the flight that departed Athens on Sunday, did not meet the criteria needed to occupy the emergency exit-row seat.

As part of safety guidelines, passengers in such seats need to meet requirements such as being in good health, able-bodied and capable of opening the exit doors if required during an emergency.

The requirements apply to all passengers, even those who have paid to upgrade their seats for more legroom.

A Scoot spokesman, who did not specify which of the criteria the man failed to meet, said: "Our cabin crew are trained and authorised to identify and reseat customers who do not meet these requirements.

"As the customer refused to comply with crew instructions and was being unruly, auxiliary police assistance was requested to meet the flight on arrival."

The spokesman added that customers must abide by safety instructions from cabin crew, and the airline may refuse to carry passengers who pose safety risks.

Consultant Jen Pelaez, 31, a passenger on the flight, told The Straits Times that the incident started at around 3am on Monday.

She said the man remained in the seat even after the pilot stated over the public announcement system that the crew's instructions should be followed.

Ms Pelaez said: "When the plane landed, the pilot did not turn off the seat-belt sign. We could not deplane until the man went with the auxiliary police."

According to data released in Parliament by the Ministry of Transport last year, there was a yearly average of 10 incidents of unruly behaviour on flights to Singapore in the five years before last year.

Internationally, there was an unruly passenger incident for every 1,053 flights in 2017, according to the International Air Transport Association. Between 2007 and 2017, it recorded more than 66,000 such incidents.