Details added (first version posted on 11:42)
A Russian plane carrying over 220 people has been lost from radars, according to sources in the Russian and Egyptian air traffic controllers. There have been reports the plane crashed over Sinai.
Egyptian Prime Minister Sherif Ismail confirmed that the Russian plane did crash in the Sinai.
Earlier, the Egyptian air accident chief said the Russian plane had safely left Egyptian airspace and made contact with Turkish air traffic control.
Kolavia Flight 7K9268 went off radar 23 minutes after taking off the Sharm El-Sheikh International Airport, Russian sources said.
A source in the Russian air traffic controller told Ria Novosti that the plane did not contact controllers in Larnaca, Cyprus.
Some Egyptian media claim the crash site has already been discovered in Egypt.
The Airbus that was reported going off radar and crashing in the Sinai Peninsula was travelling from the Egyptian resort Sharm El-Sheikh to St. Petersburg, Ria Novosti Russian news agency reported. It belonged to Kogalymavia airline, a small airline based in Western Siberia.
Egyptian sources said there were 212 people on board when the plane went down, most of them Russian tourists. Russian sources put the number at 224.