The plane carrying 92 people went down on Sunday minutes after taking off from the airport of Sochi.
"The (plane) debris are at the depth of 27 metres one mile from the shore," (89 feet) said Rimma Chernova, a spokeswoman for the Sochi-based search and rescue operations run by the Russian emergency ministry.
Russian news agencies had earlier quoted an unnamed official as saying that the fuselage of the plane had been found, a statement local authorities did not confirm when contacted by AFP.
Chernova added that divers were planning to use a remotely-operated diving machine to determine the precise coordinates and size of the plane parts in order to understand what to do next.
Officials said earlier that the flight recorders that could contain information about the Tu-154 plane's last moments before the crash were located in its tail.
The plane carrying 92 people, including over 60 members of the Red Army Choir, went down on Sunday minutes after taking off from the airport of southern resort city Sochi, where it was refuelling on its way to Syria.
Thousands of people and dozens of ships, helicopters and drones, including deep-water diving machines, are taking part in the search operation.