Initial examination of black boxes of Russian Metrojet flight 9268 denies the reports that it was shot down by a missile, claimed a source placed with the investigating team.
However, the act of terrorism has not been ruled out officially by investigators.
Earlier, Wilayat Sinai, an Egyptian-affiliated group associated with the Islamic States of Iraq and Syria (ISIS) claimed responsibility for shooting down the Russian passenger airlines, killing all 224 people on board, the Independent reported.
The claim, however, has been denied by the Egyptian authorities.
Even top American intelligence official James Clapper has expressed doubts over extremist group's involvement in the crash, though stating that a terrorist attack could still not be ruled out.
The frustration and anger mount among victims' families over opposing accounts by the various authorities.
Holding a press conference in Moscow, Deputy Head of Metrojet Alexander Smirnov denied a technical snag as a possible cause of the crash. An external impact on the plane could be the convincible reason behind the crash, he added.
Sisi calls ISIS claims a 'propaganda'
Egypt's President Abdul Fattah al-Sisi has dismissed as "propaganda" claims that the Russian airliner was downed by an Islamist State branch, saying it was to damage the image of the country and it is too early to determine the reasons of the plane crash.
"When there is propaganda that it crashed because of ISIS, this is one way to damage the stability and security of Egypt and the image of Egypt," el-Sisi told the BBC in an interview.
"The situation in Sinai, especially in this limited area, is under our full control," he said.
He welcomed all those interested in the matter to participate in the investigation into the crash.
An Islamic State affiliate in Sinai has claimed that it brought down the plane which was bound for St Petersburg in Russia from the Red Sea resort of Sharm el-Sheikh.
Both Egypt and Russia have played down the claim by Egypt's IS branch that it brought down the plane.
Investigators are examining all possible causes as they comb the remote crash site as part of an Egyptian-led probe into the disaster that also involves experts from Russia, Airbus, and Ireland, where the aircraft was registered.
El-Sisi is expected to arrive to the UK on Wednesday after receiving an official invitation from the British government.
During his visit, the President will meet Prime Minister David Cameron to discuss strategic issues, including fighting terrorism, democracy in Egypt and economic ties.