An American satellite detected a heat flash over Sinai when the Russian airliner crashed and killed all 224 people on board on 31 October. If confirmed, this would strengthen speculation that a fuel explosion or bomb blast inside the plane caused the jet to go down.
A senior US defence official, cited by NBC News, said an infrared satellite recorded a "heat flash" when the flight came down. This could rule out a potential ground-to-air missile attack.
"The speculation that this plane was brought down by a missile is off the table," the source said. It is believed the surveillance satellite would have picked up the heat trail of any missile fired from the surface. The source added: "The plane disintegrated at a very high altitude. There was an explosion of some kind."
Though there has been no credible evidence to link the incident to a terrorist attack, officials have not yet ruled out the possibility. James Clapper, the US director of national intelligence, referring to Islamic State's (Isis) capabilities to bring down the passenger jet, said: "It's unlikely, but I wouldn't rule it out."
Flight 7K9268, run by Siberian operator Kogalymavia, was travelling from Egypt's resort town of Sham el-Sheikh to St Petersburg when it came down in Sinai. The A321-200 lost contact with ground control 22 minutes into the flight while it was cruising at an altitude of 31,000ft. There were 224 people on board - 217 passengers and seven crew members. Of the passengers, three were Ukraine nationals and the rest Russian.
Meanwhile, Russian officials have criticised the airline's latest remarks about an external influence causing the plane crash. Calling the assessment baseless, Alexander Neradko, chief of Russia's Rosaviatsia Federal Air Transport Agency, told Rossiya 24 Television: "This statement is premature and is not founded on any real facts. A lot of work is in store to examine in detail airplane components, decode and analyse data of flight recorders. It is premature and there are no grounds for drawing any conclusions about the reason of plane's disintegrating in mid-air."
Investigators have already recovered both flight recorders, commonly referred as black boxes. Officials confirm the recorders are in good condition to be examined.