The black boxes from the Air Algérie plane that crashed in the Malian desert on Thursday arrived in Paris on Monday. But ministers warned that the investigation would take a while.
French aviation investigators will use them to try to determine the cause of the crash that killed all 118 people on board.
Flags on government buildings throughout France were ordered to fly at half-mast for three days in mourning for the victims, 54 of whom were French.
Experts were on site in the desert, sifting through the debris of the plain that was almost completely disintegrated.
French Foreign Minister Laurent Fabius told a press briefing yesterday that the investigation could take a while.
"French, Algerian and Malian experts are working to recover the remains of the victims," he said. "They are working in very difficult conditions - the remains are pulverised; it is extremely hot and rainy and communications and transport are extremely difficult."
Fabius said it was too early to establish the cause of the accident, although the weather is considered the most likely reason for the plane crashing.
"All hypotheses will be examined in the context of the investigation," he insisted. "What we know for certain is that the weather was bad that night and that the crew of the plane had asked to change course and then turned around, before losing contact. The black boxes are now being examined by the French Civil Aviation Safety Bureau."
Air Algérie flight AH5017 had taken off from the Burkina Faso capital, Ouagadougou, and was bound for Algiers.
On board were also people from Burkina Faso, Lebanon, Algeria, Spain, Canada, Germany and Luxembourg.