President unable to confirm whether terrorism at play
A submarine that can operate at a depth of 3,000m (10,000 ft) is being deployed in the hunt for the black boxes of a downed EgyptAir flight.
The vessel, which has been enlisted from Egypt's oil ministry, has been sent to search the seabed of the Mediterranean, Egypt's President said.
Flight MS804 came down early on Thursday morning, south of the Greek island of Karpathos and north of the Egyptian coast.
It was carrying 66 passengers and crew from Paris to Cairo at the time and is suspected to have crashed into a part of the sea several thousand metres deep.
The plane's black boxes are yet to be found but emit a signal for four to five weeks after a crash in water.
Despite his officials previously saying terrorism was the most likely cause, Egyptian President Abdel Fattah al Sisi said.
"There is no assumption that we can make at this point. We are making efforts to search.
"It is no secret that the petroleum ministry has a submarine that can dive to 3,000 metres, and it has been deployed to search the area. All theories are possible," he added.
The oil ministry said Sisi was referring to a robot submarine used mostly to maintain offshore oil rigs.
Ships scouring the sea have already found body parts, personal belongings and wreckage from the Airbus 320.
EgyptAir Holding Company chairman Safwat Moslem said the priority was finding the passengers' remains and the flight recorders.
"The families want the bodies. That is what concerns us. The army is working on this. This is what we are focusing on," he said.
It came as the first funerals of the victims took place.
Hundreds of family and friends of air stewardess Yara Hani Tawfik gathered at St Mary and St Athanasius Church in Cairo on Sunday morning.
Others attended a Coptic cathedral in Cairo to mourn two other victims, Medhat Tanious and Wagih Moris.
On Saturday, data showing trouble in the cockpit and smoke in a plane lavatory emerged.
It provided a window into the doomed jet's last three minutes before contact was lost, with multiple alarms going off, one after another.
Experts said the short time it took to descend 38,000ft into the sea indicated that a sudden, catastrophic event brought it down.
Aviation security expert Philip Baum said: "If they lost the aircraft within three minutes that's very, very quick. They were dealing with an extremely serious incident."