Terrorists believed to be responsible for blowing up a Russian passenger jet boasted to the Islamic State of Iraq and the Levant (Isil) leadership in Syria that they had succeeded, according to the latest intelligence intercepts.
>> RELATED <<
The reports add to growing evidence that a bomb was placed on board Metrojet Flight 9268 before it took off from Sharm el-Sheikh airport, killing all 224 passengers and crew.
The apparent involvement of the leaders of Isil, in Raqqa, in helping to plot the terrorist attack will alarm Western intelligence agencies.
Until now, Isil had encouraged "lone wolf" attacks on foreign targets but had been unable to organise "a spectacular" atrocity on such a scale outside of Iraq and Syria.
"They [Isil leaders] were clearly celebrating," a US official told NBC News.
In a day of further dramatic developments, it can also be disclosed:
u?A senior British minister warned the aviation industry just days before the Russian jet crashed that one of the biggest dangers was terrorist plotters penetrating security at foreign airports;
u?Egypt's investigators said a noise was heard in the last second on the cockpit voice recording on the jet, reinforcing the likelihood that the aircraft was brought down by an on-board bomb;
u?The Isil terror group claiming responsibility was trained by an ex-Egyptian special forces officer, who turned to jihadism and went on the run;
uUK aviation and security officials shown CCTV footage from inside Sharm el-Sheikh airport were so alarmed by the lack of security they ordered the cancellation of all further flights from Britain to the Red Sea resort;
u?Downing Street admitted that it would take far longer than previously thought to evacuate Britons stranded in the resort, with officials saying it would take at least 10 days to rescue the holidaymakers, amid growing frustration and distress.
Among the "chatter" picked up by intelligence agencies, there now appears to be a series of communications between the Sinai terrorist group, affiliated to the Islamic State of Iraq and the Levant, and its leadership based in
Prior to the explosion last Saturday - 20 minutes after the Airbus 321 took off for St Petersburg - US intelligence agencies also intercepted a message from the terrorists in Sinai that warned of "something big in the area".
It is understood that details about how the plane was brought down were also intercepted, but the officials would not go into detail.
Security analysts described the latest developments as a "game changer" for Isil, also known as IS.
Mokhtar Awad, at the Centre for American Progress which specialises in studying Islamist extremism, said: "What we had seen so far were IS-inspired lone wolves but this attack appears to be the result of close, consistent operational support."
Egyptian investigators stopped short of admitting for the first time that a bomb had been placed on board but did disclose yesterday a noise was heard in the last second of the cockpit voice recording. Ayman el-Muqadem, of the investigation team, said in Cairo an analysis was underway to identify the sound.
In a ratcheting of tensions between Egypt and foreign governments and the West over the crisis, Egypt's foreign minister complained the West had failed to help the country in its war on terror and had not shared relevant intelligence with Cairo.
Sameh Shoukry said: "European countries did not give us the cooperation we are hoping for."
The foreign minister's comments came as Egypt launched an investigation into the staff and ground crew in a growing indication of an 'inside job'.
It is understood that some employees have now been put under surveillance and any links to the terror group operating in the Sinai examined.
One senior figure behind the group, who is understood to have since fled to a Libyan terror camp, was Hisham al-Ashmawy, a former officer with Egypt's special forces, who has been described as the group's "mastermind and executor". Ashmawy is thought to have trained conscripts and turned the organisation into the "most dangerous militant group" in the region.
It emerged yesterday that Lord Ahmad of Wimbledon, the aviation and transport security minister, warned an industry conference less than three weeks ago that one of the biggest dangers to civilian flights was posed by plotters getting through security measures at overseas airports.
His speech will raise questions about whether the UK government had specific intelligence of a plot at that point or that there was simply an ongoing threat to security.
Senior UK officials said last night that the decision to suspend flights to Sharm el-Sheikh was based partly on a review of CCTV footage of the airport's baggage handling systems by UK officials.
Experts from the Department of Transport looked at video of how the baggage system was run and what they saw led them to recommend grounding flights on Wednesday night.
Britain has also been demanding detailed answers from the Egyptians about how their baggage handling staff are checked.
The evacuation of British holidaymakers is now expected to take 10 days, far longer than originally promised, and could be delayed still further if Russia increases the number of aircraft taking home its own citizens.
After initially aiming for more than 20 flights a day to bring stranded Britons home, the Government now anticipates fewer than 10 a day, meaning it is likely to take until the middle of this month to complete the evacuation.
Nine British flights were expected to leave the resort last night, bringing home a further 1,600 of roughly 18,500 British visitors in Sharm el-Sheikht.
But the evacuation system - which involves hiring cargo planes to fly home passengers' checked luggage separately - could be disrupted if Russia aggressively steps up its own repatriation plans. There are around 80,000 Russian holiday makers in the Red Sea resort; the Kremlin's promise to send a fleet of 93 aircraft over the weekend failed to materialise.
Some British holidaymakers yesterday accused hotels of driving up prices for stranded passengers.
Sasha Jose, a foster carer from Milton Keynes, said her hotel had cost around pounds 70 a night as part of a package but she was now being charged pounds 130 for additional days.