Australian authorities Friday said the discovery of plane wreckage, even if found to be from MH370, would not narrow down the location of the main debris field or solve the mystery of why the jet crashed.

The wreckage, which is two-metres (six-feet) long, was found on a beach on the French island of La Reunion in the Indian Ocean and is expected to be analysed in France on Saturday.

Australian Deputy Prime Minister Warren Truss said while the part "could be a very important piece of evidence" if it was linked to MH370, using reverse modelling to determine more precisely where the debris may have drifted from was "almost impossible".

"After 16 months, the vagaries of the currents, reverse modelling is almost impossible," Truss told reporters in Sydney.

"And so I don't think it contributes a great deal in as far as our knowledge of where the aircraft is located at the present time."

Australian search authorities, which are leading the hunt for the Boeing 777 aircraft in the Indian Ocean some 4,000 kilometres (2,500 miles) from La Reunion, said they were confident the main debris field was in the current search area.

The Malaysia Airlines passenger jet was carrying 239 people when it vanished without a trace en route from Kuala Lumpur to Beijing on March 8 last year.

"We don't see any basis in this for either changing or refining our search area. We still have a very high confidence in the analysis of the satellite data," Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, told AFP on Friday.

"We can go forward from our priority search zone and we know that it is entirely possible that debris would have reached La Reunion by now but you can't go backwards with any reliability.

"We will continue with our plans to cover that area very thoroughly and we hope find the aircraft in that area."

The discovery of the debris, which experts said could be a flaperon from a Boeing 777 aircraft, did not mean other parts would start washing up on La Reunion or at nearby locations, Dolan added.

"Over the last 16 or 17 months, any floating debris would have dispersed quite markedly across the Indian Ocean," he said.

Truss said accident investigators would also be keen to examine the part, if it is from MH370, to try to find out how it may have separated from the rest of the jet and "whether there's any evidence of fire or other misadventure on the aircraft".

But Dolan cautioned it would be difficult to determine why the plane disappeared just from the possible flaperon.

"There's limits to how much you can determine from just one piece of debris and we don't think it would give us sufficient reliability to speculate too much about the rest of the debris," he added.

"We know that the main debris field associated with MH370 is going to be on the bottom of the ocean, not floating on the surface."