President Abdel Fattah al-Sisi said Sunday no theory was being favoured on why EgyptAir MS804 plunged into the Mediterranean and that Egypt was using a submarine to locate the black boxes.

The Airbus A320 carrying 66 people had crashed into the sea while flying from Paris to Cairo early Thursday, and some wreckage but not the black boxes has been found.

Egypt's aviation minister had said that terrorism was more likely than technical failure, but Sisi said in a televised address that "all the theories are possible".

"There is no particular theory we can affirm right now," he said.

Sisi said a submarine that could operate at a depth of 3,000 metres (9,800 feet) under sea level had been deployed on Sunday to search for the black boxes.

"This (submarine) moved today in the direction of the plane crash because we are working hard to retrieve the two boxes, which are the black boxes," he said.

A civil aviation official told AFP on Sunday that search teams had found none of the passengers' bodies, as the search continues.

Source: AFP