- Ukraine's military intelligence service said the Black Sea fleet ship suffered damage to the stern as well as right and left sides.
- The Kremlin is yet to comment, but some Russian bloggers confirmed the sinking of the Sergei Kotov.
Ukrainian intelligence says seven people have been killed and six more injured after a Russian patrol ship was hit and sunk in a sea drone attack.
The Sergei Kotov was allegedly hit in the early hours of Tuesday morning.
Ukraine's military intelligence service said the Black Sea fleet ship suffered damage to the stern as well as right and left sides.
The Kremlin is yet to comment, but some Russian bloggers confirmed the sinking of the Sergei Kotov.
The BBC has not been able to independently verify the extent of damage to the ship.
In a Telegram post Ukraine's Main Intelligence Directorate (HUR) said 52 crew members were evacuated.
The Sergei Kotov is one of four patrol ships completed for the Russian Navy's Project 22160. It had previously been attacked by Ukraine in September last year.
"Right now this ship is on the seabed," Ukrainian Navy spokesman Dmytro Pletenchuk said, adding a helicopter may have been on board.
According to Ukraine, the vessel played a part in the attack on Snake Island on the first day of the full-scale invasion of Ukraine in February 2022, along with the Moskva cruiser.
The Moskva was sunk by Ukraine in 2022.
Russia illegally annexed the Crimean peninsula from Ukraine almost 10 years ago. In recent months Ukraine has repeatedly hit Russia's Black Sea fleet stationed on the peninsula.
Ukraine said the cost of the sunken Sergei Kotov ship was $65m (£51.2m), adding that it was hit near the Kerch Strait, which separates Crimea from Russia.
A video posted on social media appears to show the moment when the ship was hit.
BBC Verify has looked at the video, released by Ukraine, said to be of the attack.
The vessel has similar structural features to a patrol ship of the same class as the Sergei Kotov. However, no number is visible on its side, so the footage does not make clear if it is the same ship.
No other versions of the video have appeared on reverse image searches, suggesting the video was released recently.
HUR also published a recording purportedly of the commander of the Russian Navy's 184th Brigade, responsible for the Sergei Kotov, saying the ship had been attacked by five drones.
At least 13 Russian naval ships have been destroyed or damaged since the start of the conflict, according to the International Institute for Strategic Studies think tank.
Last month, another Russian amphibious ship, the Caesar Kunikov, was sunk in a drone attack just south of the city of Yalta.
At the time, Ukraine's intelligence directorate released video of what it said were Magura V5 sea drones striking the Caesar Kunikov.
Separately, Ukraine claimed credit for a drone strike on an oil depot in the Russian border region of Belgorod on Tuesday.
Kyiv also said Ukrainian air defences had downed 18 of 22 Iranian-designed attack drones launched by Russia over the Black Sea port city of Odesa.