Authorities say traces of explosives have been found on some bodies recovered from the EgyptAir plane that crashed last May.
The Airbus A320 plunged into the eastern Mediterranean en-route from Paris to Cairo on May 19th.
All 66 people on board were killed including 40 Egyptians and 15 French nationals.
Egypt's Civil Aviation Ministry said in a statement a criminal inquiry will now begin into Flight 804.
Investigators have established a fire broke out in or near the cockpit just before the jet came down between Crete and the coast of northern Egypt.
Egypt's aviation minister had said a terrorist attack was the most likely cause.
It happened seven months after a Russian airliner crashed in the Sinai Peninsula shortly after taking off from an Egyptian Red Sea resort.
The local affiliate of Islamic State said it had planted a bomb on board, and Russia later confirmed there had been an explosion.
There were no survivors among the plane's 226 passengers and crew.