Russian airline Kogalymavia says “external influence” caused the plane crash which killed 224 people in the Sinai on Saturday.
It is the first statement to back up claims by Islamic State rebels that they downed the plane.
The Airbus A321, operated under the brand name Metrojet, crashed into a mountainous area of Egypt’s Sinai peninsula on Saturday shortly after losing radar contact near cruising altitude.
According to the BBC a senior airline official said: “The only reasonable explanation is that it was [due to] external influence.”
The aircraft’s black box recording device has been recovered but aviation experts are yet to give their conclusions on the data it held.
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.
The bodies of 144 people killed in the crash have been flown back to the Russian city of St Petersburg, where the plane had been headed from the Egyptian resort of Sharm el-Sheikh.
A second flight with more bodies is expected to arrive in St Petersburg on Monday evening.
Russian President Vladimir Putin has described the crash as an “enormous tragedy”.
“Without any doubt, everything must be done to create an objective picture of events so that we know what happened and can react accordingly,” he said.