A CHUNK of 8ft long aircraft wing washed up on a remote French island is almost certainly the evidence needed to solve the world's greatest aviation mystery, according to investigators.

The barnacle encrusted part of a flaperon – a section that helps to control an aircraft's ascent and descent - found on a La Reunion beach in the Indian Ocean is increasingly thought to belong to Malaysia Airlines Flight MH370.

The jet-liner has not been seen since vanishing off radar with 239 passengers and crew on board in March last year. Searches costing millions of pounds more than 1,000 miles of Australia using the sophisticated sonar equipment have drawn a blank.

"It is almost certain that the flaperon is from a Boeing 777 aircraft," said Malaysian Deputy Transport Minister Abdul Aziz Kaprawi.

The country's investigators have now arrived on La Reunion, just over 100 miles south-west of Madagascar, has been sent for analysis to a military unit in Toulouse as the island is under French jurisdiction.

The island lies about 2,300 miles from the broad expanse of the southern Indian Ocean where search efforts have focused, but officials and experts said currents could have carried wreckage that way, thousands of miles from a crash site.

MH370 is believed to be the only 777 to have crashed south of the equator since in its 20 year history.

If confirmed to be from MH370, experts will try to retrace its drift back to where the bulk of the plane likely sank on impact. However, they cautioned that the discovery was unlikely to provide any more precise information about the aircraft's final resting place.

Australian Prime Minister Tony Abbott, whose government has been co-ordinating the search from Perth said: "I presume that if this wreckage does turn out to be from a Boeing 777 that the analysts will do their best ... to try to work out exactly where it came from," he told Australian radio.

"I don't know how accurate that will be but I dare say it will give us some more evidence and it might enable us to further refine the search area, it might," Abbott said.

French TV showed a picture of the part with the figures "657 BB" stamped on its interior. That corresponds to a code in the 777 manual identifying it as a flaperon and telling workers to place it on the right wing, according to a copy of a Boeing document that appeared on aviation websites.

Separately, a liquid soap container label, marked Jakarta Indonesia, was part of newly-discovered debris washed onto the beach at Saint-Andre on the island.

A local man has also been pictured with the remains of luggage which he said was washed up.

The plane was travelling from Kuala Lumpur to Bejing, when it suddenly turned around and headed south down the Malaysian coastline towards Australia before it drifted off radar on March 8 2014.

Investigators believe someone may have deliberately switched off MH370's transponder before diverting the plane thousands of miles off course. Most of the passengers were Chinese. Beijing has said it was following developments closely.

The luggage part may go to a mainland French police unit that specialises in DNA tests.

The discovery has caused further anguish for the families.

Jiang Hui, 41, whose father was travelling on the flight said: "Even if we find out that this piece of debris belongs to MH370, there is no way to prove that our people were with that plane."

Ghyslain Wattrelos, a French businessman whose wife and two children were on MH370, said discovery of the debris had been "extremely painful".

"This doesn't give hope, this is a moment I have been fearing," he said.

"As long as there wasn't any evidence of a crash, of wounded, of dead or whatever, there was a little glimmer of hope for us."

Zhang Qihuai, a lawyer representing some of the families, said a around 30 relatives had agreed they would proceed with a lawsuit against the airline if the debris was confirmed to be from MH370.

In January, Malaysia Airlines declared the plane's disappearance an accident, clearing the way for a payout.

"Regardless of whether our loved ones return or not, I will definitely sue Malaysian Airlines ... they have put us through so much pain and suffering, they must be held responsible," Li Zhen, whose husband was on board.