By Haitham El-Tabei
A Russian plane that crashed in Egypt broke up "in the air" strewing fragments across a wide area, an expert says, as investigators probed the disaster that killed all 224 people on board.
President Abdel Fattah al-Sissi urged patience to determine the cause of Saturday's crash, after the Islamic State jihadist group claimed it brought down the A-321 in Egypt's restive Sinai Peninsula.
"The disintegration happened in the air and the fragments are strewn over a large area," said Viktor Sorochenko, a senior official with Russia's Interstate Aviation Committee, quoted by the Russian news agency RIA-Novosti.
Sorochenko, who is heading an international panel of experts, said it was "too early to draw conclusions" about what caused the Sharm el-Sheikh to Saint Petersburg flight to go down.
Russian officials say they need to comb through an area of about 16 square kilometres in the Sinai Peninsula.
Investigators have recovered the plane's "black box" flight recorder and the Egyptian government said its contents were being analysed.
"In such cases, leave it to specialists to determine the cause of the plane crash because it is a subject of an extensive and complicated technical study," Sisi said.
The crash site in the Wadi al-Zolomat area of North Sinai was littered with blackened parts of the plane, as the smell of burnt metal lingered in the air, an AFP correspondent said.
There were no bodies visible but soldiers guarded dozen of bags as well as black, red and orange suitcases of passengers from flight KGL 9268.
Nearby lay a tiny red jacket, probably of a child, underlining the horror of the tragedy that killed 17 children.
Officers involved in search efforts said rescue crews had recovered 168 bodies so far, including that of a three-year-old girl found eight kilometres from the main wreckage.
Flags were flying at half-mast in Russia on Sunday and entertainment television programs were cancelled as part of a national day of mourning for the victims.
Cairo said there were 214 Russian and three Ukranian passengers on board, and seven crew members.
Cairo and Moscow downplayed the claim from the Islamic State's branch in Egypt that it brought down the aircraft flown by Kogalymavia airline, operating under the name Metrojet.
Egyptian Prime Minister Sharif Ismail said experts had confirmed the militants could not down a plane at the 9000-metre altitude the Airbus 321 was flying at, while Russian Transport Minister Maxim Sokolov said the claim "cannot be considered accurate".
Germany's Lufthansa, Emirates and Air France all said they would halt flights over Sinai until the reasons behind the crash were clarified.
The IS affiliate waging an insurgency in the Sinai claimed it brought down the plane in revenge for Russian air strikes against the group in Syria.
But experts rejected the idea.
To reach a plane at that altitude "you would need hard-to-use missiles, so it seems unlikely," said Jean-Paul Troadec, former director of France's BEA aviation investigation agency.
"This requires trained people and equipment that IS does not have, to my knowledge."
Experts said a surface-to-air missile could have struck the aircraft if it had been descending, and that a bomb on board could not yet be ruled out, but technical or human error was more likely.
Kogalymavia defended the pilot, Valery Nemov, who it said had more than 12,000 hours of flying experience, including 3860 hours on an Airbus A321.