Traces of explosives have been found on victims of the EgyptAir plane that crashed into the Mediterranean in May, Egyptian investigators say.
A criminal investigation would now begin into the crash of the Airbus A320, the civil aviation ministry said.
Flight MS804 from Paris to Cairo plunged into the sea on 19 May killing all 66 people on board.
A source close to the French investigation says they have doubts about Egypt's latest findings.
They told the BBC there had been "difficulties" working with the Egyptian authorities and that their main concern was to see the remains of the French victims returned to France.
The plane had been carrying 40 Egyptians, including the 10-member crew, and 15 French nationals.
In response to Thursday's report, France's foreign ministry said investigations into the crash were continuing. It also appeared to hint that it had been kept at arm's length by Egyptian officials.
"France, like it has been from the beginning of this tragic accident, remains at the disposal of the relevant Egyptian authorities to contribute to this investigation, including with the means of its experts," it said on Thursday.
Plane manufacturer Airbus has declined to comment on the Egyptian report.
The Paris prosecutor opened a manslaughter investigation into the crash in June.
In September, French newspaper Le Figaro reported that French investigators had found trace levels of TNT on debris of the plane, but had been prevented from examining it further.
Egyptian officials denied obstructing French inquiries.
Despite both investigations, the cause of the crash has remained unclear. No distress call was made beforehand but the cockpit voice recorder revealed the pilots had fought to put out a fire.
Automated electronic messages sent out by the plane showed smoke detectors going off in a toilet and in the avionics area below the cockpit, minutes before the plane vanished.
Recovered wreckage showed signs of damage caused by high temperature and there was soot on the jet's front section.
Although there were fears that an act of terrorism might have brought the plane down, no group has said it targeted the plane.
The Egyptian ministry said on Thursday that, under Egyptian law, state prosecutors would take the investigation over "if it becomes clear to the investigative committee that there is criminal suspicion behind the accident".
The crash came seven months after a Russian passenger plane was brought down by a bomb over Egypt's Sinai peninsula, killing all 224 people on board.
An Egyptian affiliate of the Islamic State group said it was behind that attack. However, there was no such claim following the crash in May.
The EgyptAir plane had taken off from Paris' Charles de Gaulle airport where security has been tight since the jihadist attacks of November 2015.
Analysts say that in the two days before the crash, the plane had travelled to Egypt, Tunisia and Eritrea, leaving open the possibility that a bomb could have been planted before its arrival in Paris.