The Boeing 747-400 with 332 passengers and 17 crew on board took off shortly before 2pm from Changi airport in Singapore. But after 25 minutes, the pilots detected problems with an engine and decided to turn back.

"It turned back because of a technical defect in the No 2 engine," said an airline spokesman. "I understand [the captain] shut it down and decided to turn back. It's his decision."

He said the engine was being checked but that he had no information on the nature of the problem. Singapore Airlines planes were forced to turn back "from time to time", he said, declining to specify how often such incidents occurred.

One passenger, Maria Atkinson, said several fire engines had been deployed at Changi airport, but the aircraft landed safely.

Singapore's national carrier suffered the first fatal accident in its 28-year history on October 31, when a Boeing 747-400 bound for Los Angeles crashed on take-off in Taipei, killing 82 people. The plane hit construction equipment when the pilot tried to take off from a runway closed for repairs.