A Cathay Pacific plane has landed safety in Darwin after it was forced to divert due to a suspected engine problem this morning.

The Airbus A350-900 was flying from Hong Kong to Melbourne and was over Katherine in the Northern Territory when it was forced to turn back to Darwin.

The plane touched down just before 8am (local time) to waiting emergency services, who left shortly after the plane had safely landed.

Passenger Paul Nicholson told 9NEWS the crew had been very professional.

"The pilot said it was an engine issue," said.

"The problem engine was shut down over Katherine."

He said it was very quiet on board after the plane had pulled in to the international terminal.

"We are all seated - no panic or anything like that."

Mr Nicholson said they had been told another plane would be sent to pick them up and passengers were served breakfast as they waited.

Cathay Pacific have just released the following statement:

"Cathay Pacific flight CX 105, which departed from Hong Kong on 24 May 2019 to Melbourne, diverted to Darwin where it landed uneventfully. Our number one priority is the safety of our passengers and crew. The flight was diverted as a precautionary measure due to a technical issue with the operating aircraft, an Airbus A350-900 aircraft.

"Cathay Pacific is dispatching another aircraft to operate the flight to Melbourne. Alternative arrangements are also being made to ensure all affected customers reach their final destination. Meanwhile, the passengers are being looked after inside the terminal with refreshment vouchers provided.