Egyptian air accident investigators say traces of explosives have been found on the remains of victims of an EgyptAir flight that crashed en route from Paris to Cairo.

Flight MS 804 plunged into one of the deepest parts of the Mediterranean Sea on May 19, killing all 66 people on board.

On Thursday, Egypt’s investigation committee issued a statement saying the coroner had found traces of explosives on the remains of some victims.

It gave no more details but said its findings were sent to prosecutors investigating foul play.

A judicial source said the prosecution had not received details about the explosives traces but would include the coroner’s findings in its inquiries.

An Egyptian source familiar with the matter said Egypt had informed France months ago about its findings but French investigators had requested more time to study them.

Paris newspaper Le Figaro reported in September that French investigators had seen trace levels of TNT on the plane’s debris but were prevented from further examining it. Egyptian officials denied at the time obstructing French inquiries.

France’s Foreign Ministry said the causes of the crash were still being investigated and appeared to hint that it had been kept at arm’s length.

“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.

Two Western sources briefed on the investigation expressed reservations about the explosives findings and said a technical cause remained the most likely.

One of the sources said the traces of explosives reportedly found appeared to be identical to samples previously held in stock, whereas there would usually be tiny forensic differences.

Audio from the flight recorder mentions a fire on board the plane in its final moments and analysis of the flight data recorder showed smoke in the lavatory and avionics bay.