The hunt for missing Malaysia Airlines Flight MH370 has uncovered a previously uncharted shipwreck, leading officials to say Wednesday that if the plane is in their search zone they will find it.

The Australian-led team is scouring the southern Indian Ocean seabed in hope of finding the final resting place of MH370, which vanished on March 8, 2014 en route from Kuala Lumpur to Beijing.

No wreckage from the flight, which was carrying 239 people, has ever been found.

In an update on the search, the Australian Transport Safety Bureau said it had spotted "multiple small bright reflections" on the otherwise featureless seabed which warranted close inspection.

Data from a high-resolution sonar scan using an autonomous underwater vehicle revealed possible items, mostly only about the size of a cricket ball, some 3,900 metres (12,795 feet) underwater.

While the debris field appeared to be of man-made origin, it failed to have all the characteristics of a typical aircraft debris field so authorities sent down an underwater camera which discovered the shipwreck.

"It's a fascinating find," said Peter Foley, director of the operational search for MH370. "But it's not what were looking for."

Images clearly showed an anchor, along with other objects which the searchers said were man-made.

Foley said officials were not pausing in the search for MH370, whose disappearance is one of aviation's great mysteries.

"Obviously, we're disappointed that it wasn't the aircraft, but we were always realistic about the likelihood," he added in a statement.

"And this event has really demonstrated that the systems, people and the equipment involved in the search are working well. It's shown that if there's a debris field in the search area, we'll find it."

The search for the aircraft has been a complex undertaking, with Australia concentrating on a remote area of the southern Indian Ocean far off its west coast spanning 60,000 square kilometres (23,166 square miles).