Since Russia invaded nearly three years ago Ukraine has constantly developed its drone industry, launching increasingly long-range strikes on Russia.

"For the first time, the Defence Intelligence of Ukraine's kamikaze drones hit enemy ships in the Caspian Sea," a source in the Defence Intelligence of Ukraine said.

The drones allegedly hit the "Tatarstan" and "Dagestan" missile ships in the city of Kaspiysk in Dagestan, according to the same source.

Russian authorities in Dagestan, bordering the Caspian Sea, said they had destroyed a drone but did not acknowledge any damage.

"The security regime at civil and military facilities has been strengthened," the regional administration said on Telegram.

Ukraine said the strikes it regularly launches over Russia's territory are fair retaliation for Russian attacks on its own territory.

Overnight Tuesday to Wednesday, Russia launched two missiles and 63 drones against Ukraine. Ukrainian air defence said it had disabled at least 38 of the drones.