"We're looking at all possibilities, but none is being favored over the others because we have absolutely no indication on the causes (of the crash)," Ayrault told French television, AFP reported.
The A320 plane of EgyptAir airline en route from Paris to Cairo disappeared from radars some 280 kilometers from the Egyptian coast early on Thursday.
Egypt’s Civil Aviation Ministry later confirmed that the plane had crashed.
There were 66 people onboard from 12 countries - 56 passengers, including three children, and ten crew members.