A distress signal was received from EgyptAir flight MS804 by an Egyptian military unit, officials have said.
The Egyptian Civil Aviation Ministry said the unit received the signal from the plane at 4.26am local time (2.26am GMT).
It was earlier reported there had been no distress calls from the flight.
Work has begun on analysing data from the two black boxes from the fated EgyptAir flight that crashed into the sea in May.
French air accident investigators confirm the signal detected earlier is from a flight recorder.
The head of Egypt's forensics authority said it is 'too early' to know what caused the EgyptAir plane to crash into the Mediterranean sea.