France's air crash investigation agency is studying a piece of plane debris found on Reunion Island off the east coast of Africa but it was too early to say if it came from missing Malaysia Airlines Flight MH370, a spokesman said on Wednesday.
A source familiar with the matter said the debris was most likely from a Boeing 777, but that it was not yet established if it was from MH370.
A U.S. official said air safety investigators had a "high degree of confidence" the debris was from the same model as MH370, the Associated Press reported.
The official said investigators, including a Boeing air safety investigator, had identified the component as a "flaperon" from the trailing edge of a 777 wing, AP reported.
The spokesman for French investigation agency BEA said the part had not been identified.
No trace has been found of MH370, which disappeared in March last year carrying 239 passengers and crew while en route from Kuala Lumpur to Beijing, in one of the greatest mysteries in aviation history. Most of the passengers were Chinese.
Search efforts led by Australia have focused on a broad expanse of the southern Indian Ocean off Australia.
"At this point in time the BEA is studying the information on the airplane part found in La Reunion, in coordination with our Malaysian and Australian colleagues, and with the judicial authorities," the BEA spokesman said in an email.
"The part has not yet been identified and it is not possible at this hour to ascertain whether the part is from a B777 and/or from MH370."
Malaysia said it had sent a team to Reunion Island to verify whether the washed-up debris was from MH370. The island is French Indian Ocean territory.
The Australian Transport Safety Bureau (ATSB) said it was working with Boeing and other officials.
"We know about it and we are trying to work with our French colleagues to try and figure out if this is from MH370. It could take some time," Chief Commissioner Martin Dolan told Reuters.
"It could take today or longer than that for us to ascertain that."
Boeing declined to comment.
The BBC quoted an aviation security expert who said the part had "incredible similarities" to a wing flap from a Boeing 777.
But the BBC also noted that there had been other crashes much closer to the island. The part is roughly 2-2.5 meters in length, according to pictures of the debris.
A local official on Reunion cautioned about rushing to conclusions.
"People are getting ahead of themselves over this," Eric Chesneau, an officer in the air transport police, told Reuters in response to speculation on social media. "It is more than likely plane debris, (but) we don't know what exact part it may be."