Egypt's president has dismissed claims that a Russian passenger jet was downed by a branch of Islamic State (IS) as propaganda, after the airline said the crash which killed all 224 people on board was due to "external" factors.
Analysis of the "black boxes", which could solve the mystery of what happened to the doomed jet, is expected to begin on Tuesday (local time) according to Egyptian officials.
Russia's government commission overseeing the crash probe is also due to meet.
President Abdul Fattah al-Sisi's remarks came as a top US intelligence official said it was "unlikely" IS was involved in the crash of the Kogalymavia Airbus A-321 over the Sinai peninsula on Saturday.
"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," Sisi told the BBC, using an alternative acronym for IS.
"Believe me, the situation in Sinai – especially in this limited area – is under our full control," he said.
Both Cairo and Moscow have played down a claim by Egypt's IS branch that it brought down the plane which was bound for St Petersburg in Russia from the Red Sea resort of Sharm el-Sheikh.
And on Monday, the US Director of National Intelligence James Clapper said that while he could not rule out IS involvement, he thought it "unlikely".
"We don't have any direct evidence of any terrorist involvement yet," he said.
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.
Senior Kogalymavia executive Alexander Smirnov said on Monday that "no technical failures" could account for why the Airbus 321 would have broken up in mid-air.
"The only explanation is some kind of external action," Smirnov told a news conference in Moscow, without elaborating, adding that the jet was in "excellent technical condition".
He said the firm had ruled out a technical fault or human error and that the plane had sustained "significant damage to its construction that did not allow it to continue the flight."
President Vladimir Putin has described the crash, Russia's worst air disaster, as a "huge 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.