The Russian plane crash in Egypt last week was not due to technical failures, French aviation officials familiar with the investigation have told the BBC.
Other French officials said the flight data recorder suggested a "violent, sudden" explosion caused the crash, killing all 224 people on board.
Intercepted militant calls indicate a bomb was put in the hold before take-off, according to UK officials.
Militants linked to the Islamic State group (IS) say they downed the plane.
The Metrojet Airbus A321 was flying from Sharm el-Sheikh to St Petersburg when it came down in Sinai last Saturday. Most of the victims were Russian.
The Sinai Province militants have not said how they downed the plane. IS has called for a war against both Russia and the US over their air strikes in Syria.
French air accident investigators cited by AFP news agency said the flight data recorder had shown that "everything was normal during the flight, absolutely normal, and suddenly there was nothing". A similar conclusion was drawn by another investigator speaking to France 2 television.
French investigators are involved because the French company Airbus manufactured the plane.
The American network NBC, quoting unnamed US officials, said on Friday that communications had been intercepted between IS officials in Syria and people in Sinai about how the jet had been brought down.
"They were clearly celebrating," NBC quoted the official as saying.
President Vladimir Putin has suspended all Russian flights to Egypt and asked for up to 50,000 Russian holiday-makers currently in Egypt to be brought home.
Mr Putin had a telephone conversation with Egyptian President Abdul Fattah al-Sisi, agreeing to continue "active co-operation" on flight safety, a statement from the Kremlin said.
Analysis: Sally Nabil, BBC News, Sharm el-Sheikh
The Russian decision to suspend flights to Egypt is a major blow to tourism, which is a lifeline to the Egyptian economy. More than 30% of the tourists who visit Egypt each year come from Russia.
Now the picture has become increasingly grim. Shopkeepers and hotel owners are pretty worried. "I don't know what tomorrow is going to bring us. We are already suffering," a shopkeeper tells me.
The tourism industry has been struggling since the revolution in 2011, due to political uncertainty. In recent months, there was a relative sense of stability so things took a better turn.
But after the latest developments, it's hard to tell when tourism will recover.
The timing of the plane crash couldn't be worse - autumn and winter are supposed to be the peak of the tourist season in Egypt.
Known for its warm weather, bright sunshine and lovely beaches, the country was getting ready for some busy weeks. But the beautiful landscape won't be enough at the moment to attract tourists.
The UK has suspended flights to Sharm el-Sheikh and is flying Britons home. It estimates that 19,000 of its nationals remain stranded in Sharm el-Sheikh.
Since Wednesday, several countries have restricted travel to Sharm el-Sheikh. They include Belgium, the Netherlands and Germany.
The US has announced it is stepping up security screening of items on US-bound flights from some airports in the Middle East. The Homeland Security statement did not say which airports it was targeting.
Tourism contributed more than 12% to Egypt's economy in 2013 and the latest measures will hit it hard, analysts say. One in five foreign tourists in Egypt is Russian.
Sinai Province militants
- Most active insurgent group in Egypt, with 1,000-1,500 members
- Operating in Sinai Peninsula since 2011
- Pledged allegiance to Islamic State group in November 2014
- Carries out suicide bombings, shootings, beheadings; dozens of Egyptian soldiers killed.