The search is continuing for missing EgyptAir flight 804, which disappeared from the radar while carrying 66 passengers and crew from Paris to Cairo.
Authorities are scouring a wide area south of the Greek island of Crete for wreckage, more than 24 hours after the Airbus 320 lost contact.
The Greek defence minister Panos Kammenos says the plane swerved wildly before plummeting into the sea.
The Egyptian military says that no distress call was received from the pilot. The country's aviation minister Sherif Fathi says the likelihood the plane was brought down by a terror attack is "higher than the possibility of a technical failure".
Meanwhile the distressed relatives of some of those on board have spent the night in a hotel in Cairo while they await news.
France's foreign minister Jean-Marc Ayrault said on Friday there is "absolutely no indication" of the cause.
The junior minister for transport, Alain Vidalies, said on France-Info radio that "no theory is favoured" at this stage and urged "the greatest caution".
A French military Falcon jet is helping in the search for debris. Vidalies said France could offer undersea search equipment and experts.
Amid fears it was an extremist attack, Vidalies defended security at Charles de Gaulle Airport, saying staff badges are revoked if there is the slightest security doubt.