Russia’s Black Sea fleet is headquartered in Sevastopol, in the occupied Crimean Peninsula. Russia annexed Crimea back in 2014.
But the Kremlin’s forces are in defence mode in the Black Sea, and are “struggling to exercise effective sea control”, the MoD said in its daily intelligence bulletin.
The MoD said that Russia’s Black Sea vessels “continue to pursue an extremely defensive posture”, although its patrols are largely contained to the Crimean coastline.
It added: “This contrasts with heightened Russian naval activity in other seas, as is typical for this time of year.
“The Black Sea Fleet continues to use long-range cruise missiles to support ground offensives but is currently struggling to exercise effective sea control.”
The MoD then pointed to a number of key blows to the Russian fleet since the February invasion got underway.
It said: “It has lost its flagship, MOSKVA; a significant portion of its naval aviation combat jets; and control of Snake Island.”
The Russian warship, Moskva, sank back in April, and was widely seen as a heavy blow to the Russian military.
Ukrainian forces attacked the ship with Neptune missiles, before the warship succumbed to a fire.
In a defiant response, the Ukrainian fighters swore at the Russian forces, telling them to “go to hell”.
The Black Sea has become one of the key battlegrounds in the invasion, with the MoD previously saying that blasts in Crimea have significantly impaired Russian capabilities.
The ministry said last week that explosions at the Saky airfield in Crimea have “significantly degraded” the Black Sea fleet.
The MoD said the blasts cost the Russian forces eight combat jets.
Russia claimed that no aircraft sustained damage in the blasts, but satellite imagery revealed that as many as ten planes had been impacted.
Ukraine has not claimed responsibility for the blasts, but a post and video released by the country’s defence ministry taunted Russia over the losses.
The caption read: “Unless they want an unpleasantly hot summer break, we advise our valued Russian guests not to visit Ukrainian Crimea.
“Because no amount of sunscreen will protect them from the hazardous effects of smoking in unauthorised areas.”