(BBC) - Australian PM Tony Abbott has said the "baffling mystery" of Flight MH370 is closer to being solved, after Malaysia announced that a fragment found in Reunion was part of the missing plane.

PM Najib Razak said experts examining the debris in France had "conclusively confirmed" it was from the aircraft.

However investigators have stopped short of confirming the link, saying only that it is highly likely.

Australia says it remains confident it is searching in the right area.

The Malaysia Airlines plane was travelling from Kuala Lumpur to Beijing on 8 March 2014 when it vanished from radar. It had 239 people on board.

What we know about the journey of MH370

Relatives say find 'proves nothing'

The debris found on the remote French island in the Indian Ocean a week ago - a wing part known as a flaperon - was the first possible trace.

The part was flown to a military laboratory in the French city of Toulouse where experts were carrying out their second day of tests on Thursday.

Who has said what on the flaperon?

• Malaysian PM: "Experts have conclusively confirmed that the aircraft debris found on Reunion Island is indeed from MH370."
• Malaysia Airlines: "This is indeed a major breakthrough for us."
• French investigators: "There exists a very high probability that the flaperon indeed belongs to Flight MH370."
• Australian PM: Debris "does seem to indicate the plane did come down more or less where we thought it did".
• Australian search team: "It is heartening that the discovery of the flaperon is consistent with our search area."
• Passenger's relative, Sara Weeks: "After 17 months, we need definite answers."

Will the debris lead us to MH370?

Following the earlier tests, Mr Najib held a news conference in Kuala Lumpur to announce that investigators had "conclusively confirmed that the aircraft debris found on Reunion Island is indeed from MH370".

This would "at least bring certainty to the families", he said.

French prosecutor Serge Mackowiak said only there were "very strong indications" this was the case, and that confirmation would only come after further tests.

The BBC's Hugh Schofield in Paris said Mr Mackowiak's caution did not suggest he had doubts, but that he was exercising legal caution.

BBC transport correspondent Richard Westcott says aircraft parts have individual serial numbers on them that airlines should be able to identify.

Mr Abbott later told reporters that the find "does seem to indicate the plane did come down more or less where we thought it did".

"It suggests that for the first time we may be a little bit closer to solving this baffling mystery," he said.

But he said the Australian-led search for the body of the plane would continue as "we owe it to the hundreds of millions of people who use our skies".

The Australian Transport Safety Bureau (ATSB) has been co-ordinating the deep-sea hunt in the southern Indian Ocean, where the plane is believed to have gone down, thousands of miles from Reunion.