An Egyptian submarine is backing up search efforts for the black boxes of an EgyptAir plane that crashed three days ago with 66 people on board, President Abdel-Fattah el-Sisi said on Sunday.
He added that the submarine, operated by the Oil Ministry, was dispatched earlier on Sunday to the Mediterranean Sea where the Airbus A320 had crashed.
The two black boxes - cockpit voice and flight data recorders - can provide clues to what caused the airliner to plunge into the sea.
Smoke was detected on the jet shortly before its crash on Thursday, the French air accident investigation agency BEA said on Saturday, confirming earlier news reports.
Al-Sissi cautioned against making conclusions about the cause of the crash.
"We should not jump to conclusions and insist on a certain supposition at this stage," al-Sissi said in televised remarks, his first since the tragedy occurred.
"Once the findings of investigations are completed, they will be made public immediately."
The Egyptair plane vanished early Thursday shortly after leaving Greek airspace en route from Paris to Cairo.
The airliner was flying at a height of 37,000 feet (11,300 metres) when it went missing about 45 minutes before its expected landing in Cairo.
Before disappearing from radar, data indicated that the aircraft swerved sharply and then began to make a steep descent, Greek authorities said.
Body parts, luggage and debris from the plane have been recovered.
The crash came in the wake of two other incidents involving Egyptian aviation.
In March, an Egyptian man used a fake explosive belt made of mobile phone covers and cables to force an Egyptair flight to land in Cyprus.
In October 2015, a Russian passenger jet broke up in mid-air shortly after take-off from the resort of Sharm el-Sheikh in Egypt's Sinai Peninsula, killing all 224 people on board.
Russian authorities said that the incident was caused by a bomb. The Islamic State extremist group, which operates in Sinai, claimed responsibility and published a photograph of a soft drink can which it said had been filled with explosives and smuggled onto the flight.