"The helicopter was carrying out take-off and landing procedures on board the Yaroslav Mudry frigate. The cause of the crash is currently being established," Vice-Adm. Viktor Mardusin said.
The Yaroslav Mudry is currently undergoing sea trials and is due to join the Baltic Fleet by the end of the year.
A spokesman for the Baltic Fleet said that there were five people on board the helicopter, including two pilots, and they all survived. He added that the crash had occurred after the helicopter's blades grazed the frigate.
"[The helicopter]...fell onto the deck of the warship and then into the sea, where it eventually sank," he said.