Audio from the recorder of EgyptAir flight MS804 suggests there was a fire on board the plane in its final moments, the investigation committee said on Saturday.
The word "fire" is heard in the cockpit voice recording from the plane before it crashed into the Mediterranean in May.
The investigators had earlier said that the other black box retrieved from the crash site, the data recorder, confirmed that smoke alarms had sounded on board, while soot in the wreckage indicates a fire.
"The committee had started listening to the cockpit voice recordings before the occurrence of the accident; where the existence of 'fire' was mentioned," the investigation committee said in a statement.
"Still it is too early to determine the reason or the place where that fire started," it said.
The data recorder points to smoke signals indicating fires in the lavatory and avionics section of the plane, according to the committee.
The data on the voice recorder had been downloaded earlier this month after the recorder was repaired.
The flight had set off from Paris to Cairo when it disappeared from radar over the Mediterranean. All 66 people onboard were killed in the crash.
Egyptian investigators have confirmed the aircraft made a 90-degree left turn followed by a 360-degree turn to the right before hitting the sea.
The latest committee statement said the search for the remains of passengers has ended.
The ship conducting the search "reached the port of Alexandria today after the end of its mission, which had been extended for the second time, after making sure of the recovery of all human remains at the site of the accident," it said.
Both the Egyptian and French judiciary have opened investigations into the mysterious incident, without ruling out a terrorist attack.
Egypt's aviation minister had initially said an attack was the more likely explanation, but President Abdel Fattah al-Sisi said there was no theory being favoured yet.
EgyptAir said last week that advance compensation payments of $25,000 will be offered to the families of the 66 people killed in the crash.
The payments are separate to those expected from insurance companies on behalf of various parties which will depend on the investigation into the disaster.