If confirmed by analysis of the debris, which will be flown to France on Saturday, the discovery would mark the first breakthrough in a case that has baffled aviation experts since the plane disappeared 16 months ago with 239 people on board.
"I believe that we are moving closer to solving the mystery of MH370. This could be the convincing evidence that MH370 went down in the Indian Ocean," Malaysia's deputy transport minister Abdul Aziz Kaprawi told AFP.
French officials said analysis of the wing part would begin on Wednesday, along with an examination of parts of a suitcase discovered near the debris on the French island of La Reunion.
However, authorities have warned one small piece of plane debris is unlikely to completely clear up one of aviation's greatest puzzles.
The Malaysia Airlines flight was one of only three Boeing 777s to have been involved in major incidents, along with the downing of flight MH17 over Ukraine last year and the Asiana Airlines crash at San Francisco airport in 2013 that left three dead.
The wing component bears the part number "657BB", according to photos of the debris. "From the part number, it is confirmed that it is from a Boeing 777 aircraft. This information is from MAS (Malaysia Airlines)," Aziz told AFP.
Martin Dolan, chief commissioner of the Australian Transport Safety Bureau, which is leading the search for the passenger jet, said the agency was "increasingly confident that this debris is from MH370."
Paris prosecutors said three judges leading the French side of the investigation would meet Monday with a team of Malaysian experts and a judicial official who have flown in, along with French police.
Meanwhile on La Reunion island, where a clean-up crew discovered the wreckage and the suitcase, dozens of curious locals scoured the rocky shore for other possible debris.
Members of the same clean-up association on Friday discovered a detergent bottle with Indonesian markings and a bottle of Chinese-branded mineral water.
Of the 239 victims, 152 were Chinese and seven from Indonesia. The beachcombers took the items to local police themselves, as no official search or security has been set up on the beach.
Australian officials played down the discovery of the luggage saying it "may just be rubbish". Flight MH370 was travelling from Kuala Lumpur to Beijing when it mysteriously veered off course and vanished on March 8 last year.
An Australian-led search has spent 16 months combing the southern Indian Ocean for the aircraft, but no confirmed physical evidence has ever been found, sparking wild conspiracy theories about the plane's fate.
In January, the fruitless search led Malaysian authorities to declare everyone on board presumed dead.
For relatives of those aboard, torn between wanting closure and hoping beyond hope that their loved ones were still somehow alive, the discovery was yet another painful turn on an emotional rollercoaster.
Australian Jeanette Maguire, whose sister Cathy was on board, said the discovery of the wreckage was "a very bittersweet feeling for all of the family, it's quite emotional."
"We're really hoping for answers that we get from this wreckage that it is MH370 so that we have some idea," she added.
Speculation on the cause of the plane's disappearance has focused primarily on a possible mechanical or structural failure, a hijacking or terror plot, or rogue pilot action.
Scientists say there are several plausible scenarios in which ocean currents could have carried a piece of debris from the plane to the island.
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".
Australian search authorities, which are leading the Indian Ocean hunt for the aircraft some 4,000 kilometres (2,500 miles) from La Reunion, said they were confident the main debris field was in the current search area.
Dolan said 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.
"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 be keen to examine the part 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 from the debris.
"There's limits to how much you can determine from just one piece of 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."
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