The Russian airline Kogalymavia has blamed "external influence" for Saturday's Sinai plane crash which killed 224 people, BBC News reports.
A senior airline official said: "The only reasonable explanation is that it was [due to] external influence."
An investigation by aviation experts using data from the aircraft's "black boxes" has yet to give its conclusions.
The head of Russia's Federal Aviation Agency said it was premature to speculate on the cause of the crash.
"This kind of talk is... not based on any proper facts," Aleksandr Neradko said on Russian TV.
Egyptian President Abdel Fattah el-Sisi also said in an interview with the BBC that it was too early to say what had caused the crash.
He called a claim from jihadis allied to the so-called Islamic State (IS) group that they had brought down the plane "propaganda".
"This is one way to damage the stability and security of Egypt and the image of Egypt," he said.
James Clapper, the US director of national intelligence, said there was no "direct evidence of any terrorist involvement yet" adding: "It's unlikely, but I wouldn't rule it out."
Russian President Vladimir Putin has described the crash as an "enormous tragedy" and expressed his condolences to the families of the victims.