"There must be training for personnel every day. Training on how to repel attacks from the air and by uncrewed boats," Defence Minister Sergei Shoigu said in a statement during a visit to the Black Sea fleet in southern Russia.

Shoigu "ordered the installation of additional firepower, large-calibre machine gun systems to defeat enemy drones," the defence ministry statement said.

The Black Sea has been a vital battleground in the two-year conflict and Ukraine claims to have destroyed more than two dozen Russian ships.

Moscow has moved many military vessels from its historic Sevastopol naval base in Crimea to the port of Novorossiysk further to the east, amid the spate of Ukrainian attacks.

Ukrainian officials have talked up military success in the Black Sea at a time when their ground forces have often been forced back or on the defensive in eastern Ukraine.

Ukraine's GUR military intelligence unit earlier this month released a video of what it said was an attack on the Sergei Kotov, a 94-metre (308-foot) Russian military patrol ship.

The footage showed a naval drone approaching the side of the vessel, before a large explosion can be seen sending fire, smoke and debris into the sky.