Victor Sorochenko, head of Russia's Interstate Aviation Committee, said it still remains too early to say what caused the crash on Saturday.
Speaking to reporters after visiting the crash site in Sinai, Sorochenko said debris was found across a 20 square km area.
Wilayat Sinai, an Egyptian jihadist group allied to Isis, has claimed credit for the crash, saying it shot the plane out of the sky "in response to Russian airstrikes that killed hundreds of Muslims on Syrian land".
Russian transport minister Maksim Sokolov has said the claim "can't be considered accurate" while Egypt's army spokesman has also dismissed it.
There have also been questions raised over the condition of the plane, with the wife of co-pilot Sergei Trukachev telling Russian state-controlled NTV "he complained before that the technical condition of the aircraft left much to be desired."
An Egyptian government official said that before the plane lost contact with air traffic controllers, the pilot had radioed in to report technical problems that he said would force him to land at the nearest airport.
Russia is observing a day of mourning after its worst-ever air disaster.
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Photo: Debris from the plane crash in Egypt Reuters