The Russian defence ministry said earlier that the plane disappeared from radars shortly after takeoff from the Black Sea resort of Sochi on Sunday. It carried eight crew and 83 passengers, including members of the world-famous Alexandrov military choir.
The ministry says rescue teams found fragments of the plane at a distance of about a mile from shore at a depth of 50-70 metres.
The Tu-154 plane, a Soviet-designed three-engine airliner, also carried nine journalists among the passengers, according to the Interfax news agency.
Defence minister Sergei Shoigu was personally co-ordinating the rescue efforts, and President Vladimir Putin has received official reports on the incident.