BBC Monitoring

Online supporters of the jihadist group Islamic State(IS) - which said it planted the bomb that brought down a Russian passenger plane over the Sinai peninsula in October - have been sharing news of the disappearance of EgyptAir flight MS804, but with little comment on the possible cause of the incident. There has been no comment from supporters of al-Qaeda.

A handful of IS supporters appeared hopeful that the group might be responsible and one speculated that it might issue a statement claiming to have brought the plane down, but there has so far been no credible indication that that might happen. 

If IS were to claim an attack on the plane, it is likely to do so within the course of the day via its official channels on the messaging app Telegram. However, it is possible that other considerations, such as the security of operatives, may delay any claim of responsibility.

Richard Westcott
Transport correspondent

An Egyptian aircraft disappearing without a mayday alert is bound to raise the spectre of terrorism. But the truth is it's far too early to say why this plane vanished.

Whatever happened, it happened too quickly for the crew to raise the alarm.

Initially, the aircraft seemed to drop off the radar at 37,000 feet, suggesting a sudden break-up. It's very rare for modern planes to simply break apart in mid air. That means an explosion was a real possibility.

But then the Greek defence minister described the aircraft making sharp turns and dropping height quickly. That suggests it was intact for longer.

Even in the worst emergencies, pilots tell me they should have time to call for help, once they've got to grips with the problem. But not always.

If you're just joining us, here is the latest news on flight MS804:

• French President Francois Hollande says the Airbus A320 crashed into the Mediterranean Sea as travelled from Paris to Cairo
• Egypt's civil aviation minister says the plane remains missing as no debris has been found
• EgyptAir says it disappeared from radar at around 02:30 Cairo time (01:30 BST), when it was 280km (174 miles) from the Egyptian coast

• EgyptAir says the plane was carrying 56 passengers - 30 Egyptians, 15 French and 10 other nationalities, including one Briton
• There were also 10 crew members on board

• Anyone concerned can call 0800 7777 0000 from any landline in Egypt and +202 259 89320 from any mobile phone or from outside Egypt

You can read more on what we know so far in this article

BBC Monitoring

The head of Russia's Federal Security Service (FSB) has said that the EgyptAir crash was "in all likelihood" a terrorist act, according to the privately-owned Interfax news agency.

"In all likelihood, this is a terrorist act, as a result of which 66 citizens of various states have been killed," Alexander Bortnikov was quoted as saying.

"We call on all interested parties, including our partners in Europe, to take joint measures to uncover those responsible for this terrorist act," he added.

We're getting more pictures through of the Airbus A320 plane (registration SU-GCC) that crashed. The first is from Brussels in January last year; the second from Istanbul in April 2014.

Image source, AP

Image source, AP

Frank Gardner
BBC Security Correspondent

Greece's Civil Aviation Authority says traffic controllers' last communication with the EgyptAir pilot found him "in good spirits".

But the authority says that when controllers tried to contact the pilot again at 03:27 local time (01:27 BST) for the handover to Egyptian airspace, "the aircraft did not respond".

You can watch the briefing live here.

BBC Monitoring

Egyptian social media is overwhelmed by news of the missing EgyptAir plane, with a clear sense of confusion on Twitter.

Some criticise the government for a lack of clarity over the incident, referring to the military denying earlier reports of having received a distress call.

"#EgyptAir, I swear to god it is not my flight and there is nothing called EgyptAir…We live in a state-like entity," tweeter @talgmashey, external said, sarcastically. Others say the plane is the responsibility of France as it left from a Paris airport.

"The real catastrophe is in the way the media and officials deal with the accident,” tweeter @M_Hosny7, external said in Arabic.

TV anchor Haitham Abu Khalil, who has more than 141,000 followers, wrote: "The fall of the EgyptAir flight is a huge event… we want transparency in the investigation about the reasons of the catastrophe #EgyptAir."

BBC Monitoring

The French newspaper Le Figaro quotes a French border police source as saying, external that investigators will be focusing their attention on ground crew at Charles de Gaulles airport, to establish whether any airport employees posed a security risk. The source said that, in the past, a number of Salafists - ultraconservative Muslims - had been detected among those with access to the areas used for the loading and unloading of aircraft.

Le Figaro also recalled that last December, the head of the Paris airports authority, Augustin de Romanet, announced that since the beginning of 2015 security clearance had been withdrawn from almost 70 employees who had worked in the most secure areas of the main Paris airports, citing one of the reasons as "radicalisation".

The missing plane made sharp turns and a descent before disappearing off radars, Greek Defence Minister Panos Kammenos says.

Frank Gardner
BBC Security Correspondent

"We have also the duty to know everything about the causes of what has happened, no hypothesis should be ruled out or preferred.

"I want that everything should be put at the disposition of the Greek and Egyptian authorities so that we can liaise with them.

"We have to send them ships and planes to make sure and to locate where the plane has crashed, and to do whatever we can to collect the debris that will allow us to know and find the truth."

Image source, EPA

In Paris, relatives of passengers are awaiting news inside the Mercure Hotel next to Charles de Gaulle airport.

In a statement, the Paris prosecutor's office has opened an investigation into the disappearance of the EgyptAir flight.

The flight took off from Paris's Charles de Gaulle airport and had 15 French nationals on board.

The prosecutor's statement mirrored that of President Hollande, saying "no hypothesis is favoured or ruled out at this stage".