A Qantas 747-400 that experienced explosive cabin decompression last year has been grounded again yesterday due to a fuel leak.

The jumbo was carrying 290 passengers from London to Sydney was a couple of hours from the West Australian coast when the leak was noticed.

A spokesman for the airline confirmed the outer engine situation on the right wing was shut down as a precautionary measure after vapour was seen streaming from the wing following a stopover in Singapore.

Qantas said that the safety of passengers on board or the aircraft was never an issue and the aircraft landed safely in Perth at 3:30pm local time.  Aviation experts confirmed that the four engine jet was capable of flying on 1 in emergency situations.

Sources say the captain chose to divert the plane to Perth where engineers could inspect the aircraft and fix the problem.

The jet was still parked on the tarmac last night in Perth.

The aircraft, which commenced service with the airline in May 1991 was involved in a serious mid-air drama last year, when a fire extinguisher exploded in the cargo bay, forcing passengers to don oxygen masks as the crew conducted an emergency decent and diverted to Manila.