The search continued on Friday for missing EgyptAir flight 804, which disappeared from the radar while carrying 66 passengers and crew from Paris to Cairo.
Authorities were scouring a wide area south of the Greek island of Crete to search for wreckage, over 24 hours after the Airbus 320 lost contact. France, Greece, Italy, Cyprus and the UK are all supporting Egypt's search effort, the defense ministry said.
Egyptian airport officials said that three French and three British investigators and an AirBus technical expert have arrived in Cairo to join an investigation into the plane crash.
Late Thursday, a senior Greek air safety official said the debris located so far in the Mediterranean sea — reported to have been "floating material"— did not belong to the missing jet.
Athanassios Binis, head of Greece's Air Accident Investigation and Aviation Safety Board, told state ERT TV that "an assessment of the finds showed that they do not belong to an aircraft."
It is not yet known what caused the crash.
The Greek Defense Minister Panos Kammenos said that the plane swerved wildly before plummeting into the sea.
The Egyptian military said that no distress call was received from the pilot. The country's aviation minister Sherif Fathi said the likelihood the plane was brought down by a terror attack is "higher than the possibility of a technical failure."
Yet France's foreign minister Jean-Marc Ayrault asserted Friday on France-2 television that there is "absolutely no indication" of what caused the crash.
The junior minister for transport, Alain Vidalies, said on France-Info radio that "no theory is favored" at this stage and urged "the greatest caution."
Amid fears the plane was downed by an extremist attack, Vidalies defended security at Paris's Charles de Gaulle Airport, saying staff badges are revoked if there is the slightest security doubt.
Families of the victims spent the night in a hotel in Cairo while they awaited the news of their loved ones. Egyptian officials said some arrived from Paris late Thursday, among them eight French relatives of the 15 French passengers on board the missing jet.
The Egyptian officials all spoke on condition of anonymity because they were not authorized to speak to the press