Sydney (AFP) - A piece of wing debris found in Mauritius is from MH370, Australian authorities said Friday as they cautioned the discovery shed no new light on the missing passenger jet's specific location.

The composite debris, recovered from the island nation in May, is the latest fragment found along western Indian Ocean shorelines linked to Malaysia Airlines MH370.

The Boeing 777 disappeared en route from Kuala Lumpur to Beijing on March 8, 2014 carrying 239 passengers and crew.

Despite an extensive underwater search in the southern Indian Ocean far off Western Australia's coast where investigators believe the plane crashed, no trace of the aircraft has been found there.

The wing part "was a trailing edge section of Boeing 777 left, outboard flap, originating from the Malaysian Airlines aircraft registered 9M-MRO (MH370)", the government agency leading the search, the Australian Transport Safety Bureau (ATSB), said in a report.

"A part number was identified on a section of the debris," the ATSB said, adding that another "unique work order number" assigned by the flap manufacturer corresponded to MH370.

Australian Transport Minister Darren Chester said investigators "remain hopeful" MH370 would be found.

"The finding of this debris... continues to affirm the focus of search efforts in the southern Indian Ocean," Chester said in a statement.

"It does not, however, provide information that can be used to determine a specific location of the aircraft."

The ATSB report came two weeks after the agency said officials had yet to link debris recovered from Madagascar by US amateur investigator Blaine Gibson to MH370 or a Boeing 777.

Officials also said the debris found in Madagascar was not exposed to fire, quashing earlier speculation.

The failure to locate any debris in the search zone has fuelled speculation the plane may have crashed outside the area.

Several pieces of debris linked to the flight have been discovered along western Indian Ocean shorelines -- in Mozambique, South Africa and Mauritius.

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The Mauritius part is the third fragment to be confirmed as coming from MH370. Malaysia said in mid-September that debris found in June off Tanzania came from the doomed airliner.

The first piece found -- a two-metre (six-foot) wing part known as a flaperon that washed up on the French Indian Ocean island of Reunion in July 2015 -- was confirmed by French authorities as from MH370.

More than 110,000 square kilometres of the search area has been scoured so far, Australia said this week, adding that the hunt was set to be completed in December.