Investigators in Australia on Monday were examining a wing flap found last month on an East African island that is suspected to be from the missing Malaysian airliner, officials said.

The "large piece of aircraft debris" arrived at the Australian Transport Safety Bureau headquarters in the capital, Canberra, for examination as part of the search for Malaysia Airlines Flight 370, said a joint statement by Australian and Malaysian government authorities.

"The large piece of what is likely to be a wing flap" was found June 23 by locals on Pemba Island, off the coast of Tanzania, the statement said.

Australian technical specialists were working with Malaysian investigators to determine whether the debris was from the Boeing 777 that vanished with 239 people on board after flying far off course during a flight from Kuala Lumpur, Malaysia, to Beijing on March 8, 2014.

The Transport Safety Bureau has so far examined four pieces of debris and found that they were almost certainly from Flight 370, which is thought to have crashed in the Indian Ocean southwest of Australia.

Another piece of wing found a year ago on La Reunion Island, off the African coast, was positively identified by French officials.

The bureau is overseeing a sonar search of 46,000 square miles of seabed in the hunt for Flight 370's crash site.

Australian Transport Minister Darren Chester said fewer than 3,900 square miles had yet to be searched. The underwater search has not yielded a single clue so far.