Malaysia's Prime Minister Najib Razak confirms the debris found on Reunion Island is from missing Malaysia Airlines flight MH370 in Kuala Lumpur, Malaysia, early August 6, 2015. [Photo/Agencies]

KUALA LUMPUR - Malaysia confirmed early on Thursday that a piece of a wing washed up on an Indian Ocean island beach last week was from Malaysian Airlines flight MH370, the first trace of the plane found since it vanished last year with 239 people on board.

"Today, 515 days since the plane disappeared, it is with a heavy heart that I must tell you that an international team of experts have conclusively confirmed that the aircraft debris found on Reunion Island is indeed from MH370," Prime Minister Najib Razak said in an early morning televised address.

"I would like to assure all those affected by this tragedy that the government of Malaysia is committed to do everything within our means to find out the truth of what happened," Najib said.

The announcement, by providing the first direct evidence that the plane crashed in the ocean, closes a chapter in one of the biggest mysteries in aviation history, but gives victims' families little clue as to why it disappeared.

"It's not the end," said Jacquita Gonzales, who lost her husband Patrick Gomes, a flight attendant.

"Although they found something, you know, it's not the end. They still need to find the whole plane and our spouses as well. We still want them back," she said.

The airline described the discovery as "a major breakthrough for us in resolving the disappearance of MH370.

"We expect and hope that there would be more objects to be found which would be able to help resolve this mystery," it said in a statement issued as soon as Najib had spoken.

The fragment of wing was flown to mainland France after being found last week covered in barnacles on a beach on France's Indian Ocean island of Reunion.

Despite the Malaysian announcement that the wing was confirmed as coming from MH370, prosecutors in France, where it was still Wednesday evening, stopped short of declaring they were certain, although they said there was a very strong likelihood that was the case. A piece of luggage also found in Reunion would be examined by French police.

"The real work is yet to begin" in inspecting the wing fragment, John Goglia, a former member of the US National Transportation Safety Board, told Reuters.

"They will identify everything they can from the metal: damage, barnacles, witness marks on the metal. They're going to look at the brackets (that held the flapron in place) to see how they broke. From that they can tell the direction and attitude of the airplane when it hit. There's a lot to be told from the metal."

The examination of the part is being carried out under the direction of a judge at an aeronautical test facility run by the French military at Balma, a suburb of the southwestern city of Toulouse, and witnessed by Malaysian officials.

Officials from the United States and manufacturer Boeing

on hand. Boeing declined to comment.

Flight MH370 went missing on March 8 last year while en route from Kuala Lumpur to Beijing. It is believed to have crashed in the southern Indian Ocean, about 3,700 km (2,300 miles) from Reunion.

The Balma test centre specialises in metal analysis and is equipped with a scanning electron microscope capable of 100,000 times magnification. It was used to store and analyse debris from an Air France jet which crashed in the Atlantic in 2009.

The Boeing 777 was minutes into its scheduled flight when it disappeared from civil radar. Investigators believe that someone may have deliberately switched off the aircraft's transponder, diverted it thousands of miles off course, and deliberately crashed into the ocean off Australia.

In January, Malaysia Airlines officially declared the disappearance an accident, clearing the way for the carrier to pay compensation to relatives while the search goes on.

A $90 million hunt along a rugged 60,000 sq km patch of sea floor 1,600 km (1,000 miles) west of the Australian city of Perth has yielded nothing.

The search has been extended to another 60,000 sq km (23,000 sq miles) and Malaysian and Australian authorities say this will cover 95 percent of MH370's flight path.