The signal was picked up by a French navy ship that is searching for the wreckage of the Airbus A320 using devices to listen for the pings of its flight recorders, the ministry of civil aviation said.
The plane went down with 66 people on board on May 19 during a flight from Paris to Cairo.
French vessel detects signals likely from EgyptAir jet black box
Another vessel sent by a private company hired to help find the black boxes is on its way to the area carrying robots that can dive to the seabed to recover them.
The ship is due to arrive at the site within a week, the ministry said.
"Extensive search efforts are being carried out to locate the two data recorders in preparation for their retrieval," the ministry said.
The black boxes, which have enough battery power to emit signals for four or five weeks, could help investigators determine the reason for the crash.
Air tragedy: EgyptAir plane debris found off Greek isle
Investigators have said it is too soon to determine what caused the disaster although a terror attack has not been ruled out.
France's aviation safety agency has said the aircraft transmitted automated messages indicating smoke in the cabin and a fault in the flight control unit minutes before disappearing from radar screens.
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