By Joe Brock

ST DENIS, Reunion (Reuters) - Plane debris which washed up on the Indian Ocean island of Reunion and is thought to belong to the vanished Malaysia Airlines Boeing 777 was flown to France on Friday for checks officials hope could provide some insight into the disaster.

Discovery of the debris, which may finally confirm the plane crashed into the sea after veering off course from Kuala Lumpur to Beijing with 239 passengers and crew, could help end 16 months of lingering uncertainty for relatives.

Aviation lawyers said it had also rekindled efforts by family members of passengers to seek greater compensation if the part is deemed to have belonged to MH370, aviation lawyers said.

Experts hope the barnacled 2-2.5 meters (6.5-8 feet) long wing surface known as a flaperon and a fragment of luggage could yield forensic clues to the fate of Malaysia Airlines Flight MH370, which vanished without trace in March 2014.

A Malaysian official and aviation experts say it is almost certainly part of a Boeing 777. But relatives, officials, the airline and governments must await the result of tests.

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

The Air France flight is due to arrive in Paris early on Saturday and the debris, which may have stayed afloat because of air pockets in the structure, will then be delivered to a military unit near the southwest city of Toulouse specialized in analyzing aviation wreckage.

The Toulouse laboratory, which employs some 600 staff, is expected to verify the serial number of the wing-flap recovered in Reunion before conducting further tests to try and establish how it came to be separated from the rest of the plane.

CHINESE ATTENTION

Aeronautic experts will study deformation and damage to the debris to determine whether it was part of a plane that exploded in mid-air or came apart on impact with the ocean, gleaning valuable insights into the disaster. Establishing the final resting place of the plane, possibly thousands of kilometers away, would still be very difficult.

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The same unit was involved in analyzing no fewer than 650 pieces of debris from the Air France flight AF447 which crashed between Rio de Janeiro and Paris in 2009, killing 228.

The office of the prosecutor general in Paris said official examination of the debris, involving French and Malaysian judicial authorities, was to start only on Wednesday.

France 2 television 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.

A fragment of luggage that was also found in the area is being flown into France with the aircraft debris and will be sent to a unit outside Paris that specializes in DNA tests.

Zhang Qihuai, a lawyer representing the families, told Reuters more than 30 family members in China have already agreed to sue if the debris is confirmed to be a part of the missing plane.

(editing by Astrid Wendlandt and Ralph Boulton)