French investigators have formally identified a washed-up piece of plane debris found in July on a remote island in the Indian Ocean as part of Malaysia Airlines Flight 370, a Boeing 777 that disappeared more than a year ago with 239 people aboard.

Investigators have been examining the wing part, called a flaperon, since it was flown to a French aeronautical research laboratory near Toulouse last month.

Malaysian authorities had already declared that the wing fragment was from the missing jet, but until now French investigators could not say with certainty that it was the case.

The Paris prosecutor's office said in a statement that investigators used maintenance records to match a serial number found on the wing part with the missing Boeing.

"Today it is possible to state with certainty that the flaperon discovered on Reunion July 29, 2015 corresponds to that of Flight MH370," the prosecutor's statement said.

The flight's disappearance on March 8 2014 has been one of aviation's most confounding mysteries.

Until the wing flap washed ashore on July 30 on the French island of Reunion, investigators had not found a single physical clue linked to the missing plane, despite a massive air and sea search. Officials believe it crashed in the southern Indian Ocean, killing everyone aboard, but are unsure of the cause.

The discovery of the wing flap refocused the world's attention on the investigation, which many hope will finally yield clues to the plane's fate.

Australian forces are continuing their search for the plane in a desolate stretch of ocean 2,600 miles to the east of Reunion, where experts believe the plane from Kuala Lumpur to Beijing crashed.

Investigators examining the wing fragment in France are trying to glean clues into the plane's fate based on its condition, opening up even more questions:

Officials who scrutinised data exchanged between the plane's engine and a satellite determined that the jetliner took a straight path across the ocean, leading them to believe that the plane flew on autopilot for hours before running out of fuel and crashing into the water.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.