CANBERRA - AUSTRALIA'S Qantas Airways defended its maintenance and safety record on Monday after one of its 747 planes was forced to make an emergency landing in the Philippines due to a hole in its fuselage.

Qantas has been ordered to check all oxygen bottles on its fleet of 747s after investigators said an exploding oxygen bottle may have ripped a hole in the plane, triggering a loss of cabin pressure during a flight from Hong Kong to Melbourne last Friday.

Qantas chief executive Geoff Dixon said the carrier was still waiting to be given full access to the aircraft, which remains on the tarmac in Manila, but said the plane was in good condition when it left Hong Kong.

'We believe everything on that aircraft was in good shape when it took off', Mr Dixon told reporters, adding that major maintenance work on the plane had been carried out in Australia. He said he could not speculate on what caused the hole.

'Incidents do happen. This is a tremendously bad one, and it's one we regret', he said.

Qantas has 225 aircraft around the world and a reputation stretching back almost 90 years as one of the safest airlines.

Mr Dixon said the company was determined to maintain its strong safety record.

'I'd be disappointed at anything ruining Qantas' safety record. It is an enviable record', he said.

'The flip side to this of course is our reputation for operational excellence and training came through, in that our pilots and our cabin crew just performed tremendously under much pressure, during a very, very bad accident', Mr Dixon said.

Passengers reported hearing a loud bang before the aircraft rapidly lost altitude and said the Boeing 747-400 had a hole the size of a mini-van on the right of its fuselage when it landed in Manila.

Australia's Transport Safety Bureau said flight QF30 made an emergency descent from 29,000 feet to 10,000 feet. All 346 passengers and 19 crew disembarked safely. A team of Australian investigators was sent to Manila to inspect the plane. -- REUTERS