The Russian passenger jet that crashed in Egypt came down because of "external" factors with human error or a technical fault ruled out as the cause, airline Kogalymavia says.
- Airline says "external" factors, not human error or technical fault, to blame in plane crash
- Crew "lost control" of aircraft, did not make distress call
- Jet received airworthiness certificate in Ireland this year
- More bodies due to be flown to St Petersburg
The carrier's management confirmed no emergency call was made by pilots during the flight as the crew "totally lost control" and did not attempt to make any contact.
The Airbus A321 came down on Saturday killing all 224 people on board.
At a press conference, Kogalymavia deputy general director Alexander Smirnov said "some kind of external action" was "the only explanation".
Mr Smirnov did not elaborate on what kind of external action may have brought down the plane, saying that would be determined by an official investigation.
He said there had been no emergency call from the pilots to services on the ground during the flight, which took off from the Egyptian Red Sea resort of Sharm el-Sheikh and was bound for the Russian city of St Petersburg.
"The crew totally lost control and for that reason there was not one attempt to get in contact and report on the accident situation onboard," Mr Smirnov said.
The plane was "flying out of control — that is it wasn't flying, it was falling".
"Apparently by that moment the plane had received significant damage to its construction that did not allow it to continue the flight," he said.
Kogalymavia's deputy general director for engineering Andrei Averyanov noted a 2001 incident when the plane's tail section struck the tarmac on landing was fully repaired and could not have been a factor in the crash.
He said the aircraft's engines had undergone routine inspection in Moscow on October 26, with no problems found, and that in the five flights before the crash, the crew recorded no technical problems in the aircraft's logbook.
"The plane was in excellent condition," Mr Smirnov said.
Russia's labour inspectors said Kogalymavia had missed two months of salary payments to employees, RIA news agency reported.
However, a Kogalymavia representative denied the company had financial problems which could have influenced flight safety.
President Vladimir Putin described the crash as a great tragedy and he called on investigators to build an "objective picture" of what happened.
Bomb 'most likely scenario' at this point, expert says
Irish regulators say the airliner received a certificate of airworthiness earlier this year.
The jet was registered in Ireland to Willmington Trust SP Services Ltd and was leased to Russian airline Kogalymavia, a spokesman for the Irish Aviation Authority (IAA) said.
Ireland's Air Accident Investigation Unit has sent officials to Egypt to help with the investigation, the transport ministry said.
Researcher analyst at the Royal United Services Institute in London Justin Bronk said a bomb seemed to be the most likely cause, at this time.
"It's certainly interesting that it's very early that technical failure or pilot error has been ruled out," Mr Bronk said.
"The extent of the debris field over about 20 square kilometres suggests a large-scale breakup of the plane at a very high altitude.
"And also there was no transmission from the pilot — so again, it happened very quickly.
"It's very early to say, but certainly at this point, a bomb is probably the most likely scenario that makes sense."
When asked about the possibility of an act of terrorism, a Kremlin spokesman said no versions could be ruled out.
Former pilot and aviation consultant Alastair Rosenschein, who is based in London, earlier said a "bomb" or "missile" might be to blame for the plane disintegrating in the air.
"That would suggest either major structural failure on an aircraft which is extremely rare, or alternatively, it could possibly have been either a bomb or a missile which took it down," he said.
However, US national intelligence director James Clapper said he knew of no "direct evidence" terrorism was to blame for the crash.
"ISIL in a Tweet claimed responsibility for it and there is a very aggressive ISIL chapter in the Sinai," Mr Clapper said.
"But we really don't know, and I think once the black boxes have been analysed, which they have recovered, then perhaps we will know more."
Asked if Islamic State had the firepower to shoot down a jet, he replied: "It's unlikely, but I wouldn't rule it out."
Egyptian and Russian investigators have begun examining the contents of the black box recorder recovered from the airliner.
Officials earlier expressed doubt over claims from a militant group affiliated with Islamic State that it brought the plane down, saying the militants were not believed to have missiles capable of hitting the plane.
More victims' bodies to be repatriated to Russia
A second plane carrying victims of the crashed Russian jet crash was expected to leave Egypt on Monday evening, Russian officials said, as relatives prepared to identify the remains of their loved ones in St Petersburg.
Russia's emergency situations ministry did not give any indication of how many bodies would be on board.
A first plane touched down in Russia's second largest city early on Monday carrying the remains of 140 of the victims.
Family members have been providing DNA samples at a crisis centre set up close to St Petersburg Pulkovo airport, now the site of an impromptu memorial where people have brought flowers and cuddly toys to commemorate the victims, many of them children.
A representative from Russia's emergency situations ministry said that investigators had so far found 12 segments of the plane's fuselage and personal belongings.