Egypt admits bomb may have downed doomed Russian airliner

Debris of the A321 Russian airliner. Photo / Getty Images

Egypt and Russia appeared to back away from their assertions that a Russian passenger jet crashed in the Sinai desert because of a technical fault, as it was revealed that the plane broke up in the air and officials conceded the aircraft could had been brought down by a bomb onboard.

In the hours after the Airbus A321 crashed on Saturday - killing all 224 aboard and spreading debris and bodies over miles of desert - both governments were quick to say the doomed airliner appeared to be the victim of mechanical failure.

But Abdel Fattah al-Sisi, Egypt's president, was speaking more cautiously, saying it was too soon tell the cause and that an "extensive and complicated technical study" was needed.

Investigators have reportedly begun examining both of the aircraft's black boxes in the hope of learning what happened in its final moments. Photo / AP

Islamic State of Iraq and the Levant (Isil) has claimed credit for destroying the aircraft, saying it was revenge for Russia's intervention in Syria on behalf the Assad regime.

While experts believe it was flying too high to be hit by an Isil missile, an Egyptian official in the civil aviation ministry told The Daily Telegraph it was possible the plane was brought down by an explosive planted onboard.

The official said that a mechanical failure was still thought to be the most likely explanation but that it was too early to draw a firm conclusion. He confirmed the pilot had not issued any distress call, suggesting the aircraft suffered a sudden calamity.

Viktor Sorochenko, a Russian aviation official who inspected the crash site, said the Kogalymavia-operated flight "broke up in the air" as he explained why the debris was spread over eight square miles (20sq km).

"Disintegration of the fuselage took place in the air, and the fragments are scattered around a large area," he said.

Investigators have reportedly begun examining both of the aircraft's black boxes in the hope of learning what happened in its final moments.

People mourn the victims of Airbus A321 crash at Pulkovo Airport. Photo / Getty Images

A grainy mobile phone video circulated online purports to shows the moment the airliner exploded before hurtling down to earth, but its origins are unclear and it could not be verified as authentic.

However, it appeared to chime with accounts from eyewitnesses who said the plane fell flaming from the sky.

Yves Trotignon, a former French intelligence agent, noted that Isil's claim of responsibility was vague in detail. "The statement does not say they shot it down, but that they destroyed it," he told Le Parisien. "You could imagine explosives on board, or sabotage."

Terrorism experts said Isil had never claimed an attack it did not carry out. Mathieu Guidere, professor of Islamic studies at the University of Toulouse, said Isil "is very well established in the Sinai, has infiltrated almost all organisations and infrastructure, so it is quite possible that a fighter sabotaged the plane at the airport before it took off or placed a device on board".