Teams investigating the fate of a Russian airliner which crashed in Egypt's Sinai peninsula on Saturday killing all 224 on board have widened their search for bodies and debris.
So far 163 bodies have been found but the search area was extended to 15km (9 miles) after some were located at a distance from the main wreck.
Russia is observing a day of mourning after its worst air disaster.
Egypt and Russia dismissed IS claims that its militants were responsible.
Jihadists allied to so-called Islamic State in Sinai, where such groups are active, made a claim on social media that they had brought down flight KGL9268.
But Egyptian Prime Minister Sharif Ismail said experts had confirmed that a plane could not be downed at 9,450m (31,000ft), the altitude the Airbus 321 was flying at, by weapons the militants are known to possess.
President Abdul Fattah al-Sisi also urged caution on Sunday, saying the investigation into the cause was a "complicated matter" that could take months.
Russian Transport Minister Maksim Sokolov said no evidence had been seen that indicated the plane was targeted, and IS has not produced pictures or video footage to substantiate its claim.
Analysis by BBC Monitoring found that a video purporting to show the downing of a plane did not appear to be an official IS clip, and was not shared on official IS channels.
At the scene - Sarah Rainsford, BBC News, Pulkovo airport in St Petersburg
They've been reading out the names of the dead here, one by one.
There were memorial services across the country for those killed, flying back from a holiday in the sun.
The vast majority were from here, in St Petersburg. Russian officials have now joined the hunt for clues at the crash scene in Egypt - they're also recovering the bodies. The first could be flown back this evening.
Here, at the airport where flight 9268 should have arrived, there is a growing pile of flowers and toys left in memory of those who died, including 25 children.
Three airlines - Emirates, Air France and Lufthansa - have decided not to fly over the Sinai Peninsula until more information is available. Two smaller carriers, flydubai and Air Arabia, also said they would re-route flights.
British Airways and easyJet said they were not currently intending to alter their routes.
The Kogalymavia Airbus A-321 came down early on Saturday, shortly after leaving the resort of Sharm el-Sheikh for the Russian city of St Petersburg.
Russian and French investigators have joined the Egyptian-led probe, along with experts from Airbus, which is headquartered in France.
Meanwhile a Russian team has arrived at the crash site to join efforts to recover bodies, Russian media say.
Egyptian officials said some bodies had been recovered within a radius of 5km on Saturday, but that of a three-year-old girl was found 8km from the scene.
The plane's black boxes have been found and sent for analysis, officials said.
Egypt's civil aviation minister Hossam Kamal said there had been no sign of any problems on board the flight, contradicting earlier reports that the pilot had asked to make an emergency landing.
The widow of the plane's co-pilot told Russian TV her husband had complained about the aircraft's technical condition.
The BBC's Sally Nabil in Cairo says the crash has been a major blow to Egypt's already struggling tourism industry, and the Egyptian authorities are trying hard to accelerate the investigation process.
The plane was carrying 217 passengers, including 25 children, Russian transport authorities said. There were seven crew members on board.
Egyptian officials had said 213 of the passengers were Russian and four were Ukrainian, but Russian officials said at least one of the victims was from Belarus.
The bodies of 163 victims have so far been recovered and taken to Cairo.
The first bodies to be returned to Russia are expected to be flown to St Petersburg on Sunday.
One un-named official told Reuters the plane appeared to have split in two, with one part burning up and the other crashing into a rock.
Timeline: the course of flight KGL9268
05:58 Egyptian time (03:58 GMT): Flight leaves Sharm el-Sheikh, the Egyptian cabinet says in a statement
06:14 Egyptian time (04:14 GMT): Plane fails to make scheduled contact with air traffic control based in Larnaca, Cyprus, according to Sergei Izdolsky, an official with Russia's air transport agency
06:17 Egyptian time, approx (04:17 GMT): Plane comes down over the Sinai peninsula, according to Airbus
11:12 Egyptian time (09:12 GMT): Flight had been due to land in St Petersburg's Pulkovo airport