Canberra - A Sydney-bound Qantas Airways passenger jet made an emergency landing in Perth on Wednesday after a fuel leak was discovered four hours into its flight from Singapore.

The Boeing 747-400 was carrying 290 passengers and is the same plane diverted from Hong Kong to Manila in July last year after an exploding oxygen cylinder blasted a hole in the fuselage mid-flight.

A Qantas spokeswoman said there was "absolutely no link" between the two incidents and there was no danger to passengers in the latest incident. "One of the plane's engines was shut down as a precaution when the leak showed up on the controls," the spokeswoman said.