(Reuters) - Ukraine's navy said on Monday that Moscow's last naval patrol ship had left Russian-occupied Crimea, "most likely" to rebase elsewhere after Kyiv's concerted military campaign to attack the Black Sea peninsula as it battles Russian invasion.

Though it has no major warships at its disposal, Ukraine has used missiles and naval drones to inflict significant damage to the Russian Black Sea Fleet, which has long been headquartered in Sevastopol on the peninsula seized by Moscow in 2014.

Vice-Admiral Oleksiy Neizhpapa, Ukraine's navy chief, told Reuters earlier this month that Russia had been forced to rebase nearly all its combat-ready warships from occupied Crimea.

"The last patrol ship of the Black Sea Fleet of the Russian Federation is bolting from our Crimea just now. Remember this day," Navy spokesman Dmytro Pletenchuk said on Facebook.

Asked to clarify whether this was a permanent move, Pletenchuk told Reuters: "Most likely, this is a transition between bases", adding that Moscow did not usually send ships to the open sea for no reason.

He said the vessel's designation was Project 1135.

Russian authorities have not responded to requests for comment in the past about Ukrainian claims of advances in the Black Sea.

Kyiv has destroyed or damaged 27 Russian naval vessels, Neizhpapa said. In May, Ukrainian authorities said they had destroyed the last Russian warship armed with cruise missiles that was stationed on the peninsula.

Moscow's setbacks in the Black Sea come at a time when Ukrainian ground troops are on the back foot across a sprawling front and in particular in the east.

President Vladimir Putin told navy chiefs last month that Russia's fleet had been replenished over recent years and that a major modernisation was under way, including steps to "increase the combat stability of the fleet" and strengthen it.

(Reporting by Yuliia Dysa; editing by Tom Balmforth; and Tomasz Janowski)