A Singapore Airlines (SIA) plane, which caught fire soon after it made an emergency landing at Changi yesterday, forced the airport to close one of its two runways for more than four hours.

None of the passengers and crew on board Flight SQ368 were injured but travellers booked on other early morning flights faced some delays as Runway 2 was off-limits from about 7am to 11.30am.

The SIA Boeing 777-300ER with 222 passengers and 19 crew on board had left Changi Airport for Milan, Italy, at around 2am. About an hour and 45 minutes into the flight, the pilots received an engine oil warning - possibly indicating an oil leak - and decided to turn back.

Passenger Lee Bee Yee, 43, said she detected a faint whiff of what smelled like petrol. Even though the plane could have made an emergency landing at a nearby airport, its pilots decided to fly back to Changi, some two hours away.

"We were informed by the pilot that there was a leak, and that the plane would have to return to Changi Airport as it did not have enough fuel for the journey," said Ms Lee, who runs an e-commerce firm.

Changi Airport's emergency service team was on standby when the plane landed at about 6.50am. But shortly after, its right wing caught fire. Passengers were not immediately evacuated. A video shot by a passenger on the plane - that was circulating online yesterday - showed the entire wing ablaze just outside the cabin's windows.

"The blaze was quite fierce and we waited for around two to three minutes before the fire engines arrived," Ms Lee said. "Surprisingly, all the passengers were quite calm. The SQ crew were very professional in calming everyone down."

It took about five minutes to put out the blaze. Passengers eventually disembarked using mobile stairs and were taken by bus to the terminal building. The flight eventually took off at about 11am with a new plane and a fresh crew.

SIA did not say why the pilots flew back to Changi but noted that there are many factors, like the state of the aircraft and services needed on arrival, to consider when deciding where to land the plane in an emergency and that pilots can communicate with engineering and fleet management teams before acting. It did not comment on why passengers were left on the plane even as the fire blazed outside, citing ongoing investigations.

In a Facebook posting, Prime Minister Lee Hsien Loong said he was relieved that all who were on board disembarked safely. He thanked SIA and Changi Airport for responding swiftly to the incident, adding that the Air Accident Investigation Bureau is investigating the cause.

• Additional reporting by Lee Min Kok