The Egyptian military has released images of items found during the search in the Mediterranean Sea for missing Egypt Air flight MS804.
They include life vests, parts of seats and objects clearly marked EgyptAir.
The Airbus A320 was en route from Paris to Cairo with 66 people aboard when it vanished from radar early on Thursday.
Investigators have confirmed smoke was detected in various parts of the cabin three minutes before it disappeared, but say the cause is still not known.
Speaking on Saturday after meeting relatives of victims, French Foreign Minister Jean-Marc Ayrault said “all theories are being examined and none is favoured”.
Images posted on the Facebook page of the spokesman for the Egyptian Armed Forces showed life vests and other items with the EgyptAir logo.
The search has also reportedly found body parts and luggage.
The main body of the plane and the two “black boxes” which show flight data and cockpit transmissions have not yet been located.
While no bodies have been recovered, memorials have been taking place for the victims.
A service was held in a Cairo church on Saturday for air hostess Yara Hani, who was aboard the doomed plane.
The Aviation Herald said that smoke detectors had gone off in the toilet and the aircraft’s electronics before the signal was lost.
It said it had received flight data filed through the Aircraft Communications Addressing and Reporting System (ACARS) from three independent channels.
It said the system showed that at 02:26 local time on Thursday (00:26 GMT) smoke was detected in the jet’s toilet.
A minute later – at 00:27 GMT – there was an avionics alert indicating smoke in the bay below the cockpit that contains aircraft electronics and computers.
The last ACARS message was at 00:29 GMT, the air industry website said, and the contact with the plane was lost four minutes later at 02:33 local time.
ACARS is used to routinely download flight data to the airline operating the aircraft.
Confirming the data, France’s Bureau of Investigations and Analysis told AFP it was “far too soon to interpret and understand the cause of the accident as long as we have not found the wreckage or the flight data recorders”.
Agency spokesman Sebastien Barthe told Associated Press the messages “generally mean the start of a fire” but added: “We are drawing no conclusions from this. Everything else is pure conjecture.”
Philip Baum, the editor of Aviation Security International Magazine, told the BBC that technical failure could not be ruled out.
“There was smoke reported in the aircraft lavatory, then smoke in the avionics bay, and over a period of three minutes the aircraft’s systems shut down, so you know, that’s starting to indicate that it probably wasn’t a hijack, it probably wasn’t a struggle in the cockpit, it’s more likely a fire on board.”