French authorities opened a manslaughter inquiry Monday into the May crash of an EgyptAir plane that killed 66 people, saying there is no evidence so far to link it to terrorism.

Prosecutor's office spokesman Agnes Thibault-Lecuivre said the inquiry was launched as an accident investigation, not a terrorism investigation. She said authorities are "not at all" favoring the theory that the plane was downed deliberately, though the status of the inquiry could eventually change if evidence emerges to that effect.

Investigators decided to start the probe before waiting to analyze the plane's flight data and voice recorders, based on evidence gathered so far, she said, without elaborating.

EgyptAir Flight 804, an Airbus A320 en route from Paris to Cairo, slammed into the Mediterranean on 19 May. The reason for the crash remains unclear. The pilots made no distress call, and no group has claimed to have brought down the aircraft.

Search teams have recovered its two flight recorders, but they suffered damage and Egyptian investigators were unable to download information from the so-called black boxes.

The recorders' memory cards arrived Monday in Paris, Egyptian investigators said. Technicians at France's air accident investigation agency, the BEA, will attempt to clean and repair them, and then send them back to Egypt for analysis, the BEA said in a statement Friday.

While the plane was Egyptian and crashed in Egyptian waters, France can also investigate because the plane was manufactured by France-based Airbus and French citizens were among those killed.