Troubled Qantas plane lands in Singapore: AFP reporter

Fire engines immediately swarmed the aircraft as soon is it landed on the tarmac on Changi Airport.

"I can see smoke coming out of it," the reporter said.

"One of the engines on the left wing looks blown off. It is black and has jagged edges," the reporter added.

The double-decker plane, which had taken off from Singapore bound for Sydney carrying 433 passengers, dumped fuel over Indonesia before returning to the city-state's Changi Airport trailing smoke.

Six fire engines swarmed the A380 on landing, spraying liquid on it, according to an AFP reporter.

One of the engines on the left wing looked to be missing, and the area around it was black, the reporter said.

Plane debris including what appeared to be part of the tail of a Qantas jet was found in the Indonesian town of Batam, after a mid-air explosion was heard on the ground.

"I didn't see a plane crash but I heard a loud explosion in the air. There were metal shards coming down from the sky into an industrial area in Batam," witness Noor Kanwa told AFP.

A spokesman for Australia's Qantas Airways sid the plane was carrying 433 passengers and 26 crew and there were no immediate reports of injuries.

Qantas, which has never suffered a fatal crash in its 90-year history, said earlier there had "definitely" not been a crash involving one of its planes over Indonesia.

"We're just waiting on a report," a spokeswoman told AFP. "At this stage there's definitely been no crash."

The A380's very first commercial flight operated by Singapore Airlines was on the same Singapore-Sydney route in October 2007.

Since then, fuel and computer glitches have grounded several A380s and at least one Air France flight was forced to turn around and land in New York after problems with its navigation system in November 2009.