Engine Fire on Cathay Pacific Plane Flying from Perth to Hong Kong Forces Emergency Landing

An engine on a plane flying from Perth to Hong Kong caught fire shortly after take-off overnight, forcing an emergency landing in Indonesia.

A man has contacted the ABC saying his brother was onboard Cathay Pacific flight CX170 when there was a loud bang and sparks and flames.

The cabin was then reported to have gone dark.

He said about 15 minutes later the captain reported a problem with one of the engines.

The plane was diverted to Denpasar in Indonesia and the passengers were booked into a hotel.

Cathay Pacific issued a statement confirming it was investigating the engine defect.

It said the number two engine on the Airbus A330 was shutdown when the problem arose and an emergency landing was declared.

"The aircraft landed safely in Denpasar. Fire services met the aircraft on arrival," the statement read.

"There was no fire onboard and no passengers or crew were injured."

The airline said the 251 passengers onboard had been provided with hotel accommodation while the issue was being addressed.

It also said safety remains the airline's highest priority.