An EgyptAir voice recorder has revealed that staff tried desperately to put a fire out on flight MS804 before it plunged into the Mediterranean.
Earlier analysis of the plane's flight data recorder showed there had been smoke in the toilet and avionics bay while recovered wreckage from the jet's front section showed signs of high temperature damage and soot.
The Airbus A320 plunged into the eastern Mediterranean Sea en route from Paris to Cairo in May, with the cause of the crash unknown.
Today's sources has said the investigation committee remains open to all possibilities regarding what caused the crash.
But the flight deck recorder, taken to Cairo this week after being repaired at laboratories belonging to France's BEA aircraft accident agency, further indicated that a fire took hold of the plane in its final moments, the sources said.
The recordings usually capture pilot conversations and any cockpit alarms, as well as clues such as engine noise.
Last week, it was revealed the black box recorded smoke being detected in the toilet.
In a statement released last Wednesday, investigators said: "Preliminary information shows that the entire flight is recorded on the FDR since its takeoff from Charles de Gaulle airport until the recording stopped at an altitude of 37,000 feet where the accident occurred.
"Recorded data is showing consistency with SCARS messages of lavatory and avionics smoke," the committee added, referring to the Aircraft Communications Addressing and Reporting System, which routinely downloads maintenance and fault data to the airline operator.
The plane went down about halfway between the Greek island of Crete and Egypt's coastline, or around 175 miles offshore, after take-off from Charles de Gaulle Airport.
Before it disappeared from radar screens around 2.45am Cairo time, the plane spun all the way around and suddenly lost altitude.
Among the dead were British geologist Richard Osman, Captain Mohamed Said Ali Ali Shoukair, and a family of four, Faycal Bettich, wife Nouha and children Joumana, four months, and her two-and-a-half-year-old brother Mohamed.
A search vessel was still recovering bodies from the seabed on Sunday, brought up to the Mauritian-based ship John Lethbridge, which is taking them to Alexandria, Egypt, before returning to begin the search anew.
The Egyptian Aircraft Accident Investigation Committee said that the John Lethbridge had "retrieved all the human remains that were mapped at the crash location," BBC News reported.