Smoke alerts were triggered in the toilet and the aircraft's electrics, just minutes before the signal was lost, according to data published on air industry website the Aviation Herald, which said it had received flight data filed through the Aircraft Communications Addressing and Reporting System (ACARS) from three independent channels.
The fresh details follow Egyptian military's recovery of debris, passengers' belongings, body parts, luggage and aircraft seats from the ill-fated plane, even as searchers were trying to locate the crucial black boxes that could shed light on the crash.
"All theories are being examined and none is favoured," Foreign Minister Jean-Marc Ayrault told a news conference after meeting with relatives of passengers who were aboard the doomed EgyptAir Flight MS804, en route from Paris to Cairo.
"The reports circulating here and there, which by the way are sometimes contradictory, give rise too often to nearly definitive conclusions," Ayrault said.
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"Finding the plane is of course the priority, along with finding the black boxes to analyse them, which will allow us to answer legitimate questions," he said.
France's "dual goal" is to offer "solidarity with the families but also transparency... On the circumstances of this plane's disappearance," said Ayrault, who was joined by Egyptian Ambassador at the meeting with the victims' family.
Authorities earlier hinted at a terror angle to the tragedy.
The Herald said the system showed that at 02:26 local time on Thursday (05:56 IST) smoke was detected in the toilet of the Airbus A320. Just a minute later - at 05:57 IST - there was an avionics smoke alert.
ACARS is used to routinely download flight data to the airline operating the aircraft.
"(The data) doesn't tell us anything, whether it's an explosion because of a bomb or because of a mechanical fault, but immediately it narrows down the area that we're looking at," CNN aviation analyst Richard Quest said.
"We're now no longer worried about wings or what else might have happened, or other flight control surfaces," Quest added.