Qantas says it is suspending the airline's flagship A380 fleet until it is confident the planes are safe.

Passengers say they heard two loud bangs when an engine failed on board this morning's flight from Singapore to Sydney.

The airline says flight QF32, with 433 passengers and 26 crew aboard, made an emergency landing at Changi Airport and all on board are safe and well.

Qantas CEO Alan Joyce says the airline, the manufacturers and the Australian Transport Safety Bureau (ATSB) will investigate the incident.

He says the engine failure is unprecedented on board an A380.

"This is absolutely the first issue that's occurred, with this engine failure; as I said it's a significant engine failure," he said.

"As a precaution we're suspending the flights of the A380 aircraft until we're we're comfortable that we understand the reasons of this, and comfortable that we can operate the aircraft again.

"We do take our safety reputation and our safety standards unbelievably seriously and we're not going to take any risks with passenger safety."

He says the issue is not to do with aircraft maintenance.

"This is an engine issue so this is not related to the aircraft... so it's not related to any maintenance of the aircraft," he said.

"These are new aircraft, this is the first aircraft we took delivery of two years ago, the engines on the aircraft in question are new.

"So we're obviously having to work very closely with the manufacturers to understand exactly what's happened."

Mr Joyce says the Rolls-Royce engines have been in operation since the launch of the A380 aircraft two years ago.

Rolls-Royce in the UK had no comment when asked by the ABC if it plans to recommend other airlines follow Qantas's suspension.

QF32 passengers will spend the night in Singapore before being flown to Sydney in the morning. Passengers booked on other A380 flights face delays as Qantas finds seats for them on other planes.

'Loud bang'

Passenger Christopher Lee told ABC Radio's PM program that there was an explosion about 15 minutes after take-off.

"After leaving Singapore there was an explosion, there was a loud bang followed by another one, and then a rattling of the cabin", he said.

"Some of the passengers then alerted cabin staff to the fact that there was an explosion, there was smoke or something to that effect."

But Mr Lee says the landing was not too bad.

"I must say I fly on many international flights and probably do, if not one a week, sometimes two a week, and it's one of the smoothest landings I've had actually," he said.

Parts of the engine cover crashed down onto the Indonesian island of Batam, south of Singapore.

Indonesian authorities say a teacher and a student were injured when debris fell onto the roof of a school.

A Department of Foreign Affairs and Trade (DFAT) spokesperson says Australian High Commission staff are on their way to Changi to assist any Australians on board the flight.

If you are unable to contact relatives and hold concerns for their welfare, call DFAT's 24-hour Consular Emergency Centre on (02) 6261 3305 or within Australia on 1300 555 135.

Qantas operates A380 flights from Sydney and Melbourne to Los Angeles, Singapore and London.

The A380 is the world's largest passenger plane, and Qantas is one of only five airlines that currently fly the double-decker plane.

Qantas has never had a fatal accident involving a passenger jet.

In September 1999, a Qantas jumbo jet carrying 407 passengers overshot a runway and skidded into a Bangkok golf course.

In 2008 a mid-air explosion blew a minivan-size hole in the side of a Qantas 747-400 which Australian air safety investigators blamed on an oxygen bottle.

Were you on the plane? Did you witness the incident? Contact ABC News Online.

- ABC/AFP/Retuers