Black box data from the crash showed smoke alarms had sounded on board, while soot was found on the wreckage, an Egyptian-led investigative committee said on Wednesday.
"Recorded data is showing a consistency with ACARS messages (the plane's automated reporting system) of lavatory smoke and avionics smoke," the investigators' statement said. They also said they found "signs of damage because of high temperature."
Last week, the two black boxes on board the flight were sent to France for repairs after sustaining heavy damage in the crash. They were then returned to Cairo for data analysis.
EgyptAir flight MS804 was flying from Paris to Cairo on May 19 when it crashed somewhere in the Mediterranean, killing all 66 people on board. Following the recovery of some of the human remains, officials said there was likely a blast on board the plane.
Earlier, an aviation expert told DW there had likely been a fire. "There was a fire on board," said Tim van Beveren. "The system sent very clear messages. There was lavatory smoke detected. A minute later, avionics compartment smoke detected... Two minutes later, the flight control units are failing."
blc/jr (AP, AFP)