Ukraine has claimed it has sunk another Russian warship in the Black Sea using high-tech drones as Kyiv’s forces continue to take aim at targets deep behind the war’s front line.

Russian authorities did not confirm the claim.

The Ukrainian military intelligence agency said a special operations unit destroyed the large patrol ship Sergey Kotov overnight with Magura V5 uncrewed vessels that are designed and built in Ukraine and laden with explosives.

The patrol ship, which Ukraine said was hit near the Kerch Strait on Tuesday, can reportedly carry cruise missiles and around 60 crew members.

The claim by Ukraine could not be independently verified, and disinformation has been a feature of the fighting that broke out after Russia’s full-scale invasion of its neighbour in February 2022.

The private security firm Ambrey said the attack took place at the port of Feodosia, in Crimea, which Russia annexed in 2014.

Ambrey said it has seen footage taken by a crew member on a merchant vessel in the port, showing the Sergey Kotov firing at the drones.

The ship was hit at least twice, with the second strike resulting in a large blast, Ambrey reported.

The sinking of such a modern ship would be a significant loss and an embarrassing blow for Moscow, even though there are dozens of other vessels in its Black Sea fleet.

Kyiv’s forces are struggling to keep the better-provisioned Russian army at bay at some points along the largely static 1,500-kilometre (930 mile) front line, but are also taking aim at targets beyond the battlefield.

Last month, Ukraine claimed it twice sank Russian warships using drones.

On February 1st, it claimed to have sunk the Russian missile-armed corvette Ivanovets, and on February 14th it said it destroyed the Caesar Kunikov landing ship.

Russian officials did not confirm these claims.

Kyiv officials say some 20 per cent of Russian missile attacks on Ukraine are launched from the Black Sea, and hitting Russian ships there is embarrassing for Moscow.

Almost a year ago, the flagship of Russia’s Black Sea fleet, the Moskva guided-missile cruiser, sank after it was heavily damaged in a missile attack.