By Tom Balmforth and Yuliia Dysa
KYIV (Reuters) -Ukraine said on Thursday it attacked two Russian patrol ships and destroyed a sophisticated air defence system in the west of occupied Crimea, ramping up its strikes to challenge Moscow's dominance in the Black Sea region.
The attacks come a day after Kyiv said it seriously damaged a Russian submarine and landing ship undergoing repairs in a missile strike on a shipyard in the Crimean port of Sevastopol, home to the Russian Black Sea Fleet.
The Ukrainian military, in a post on Telegram messenger, said it hit two Russian patrol boats in the southwest of the Black Sea, causing "certain damage" in a morning attack.
"The (Sergei) Kotov was hit," military intelligence official Andriy Yusov told Reuters, sharing a grainy video circulated online by a Ukrainian government minister that appeared to show sea drones attacking a vessel at sea.
The Russian Defence Ministry confirmed an attack on the Sergei Kotov in a morning statement, but said the assault involving five sea drones was repelled. It made no mention of damage.
Reuters could not independently confirm the reports or the video.
The southwestern location of the attack would indicate Ukraine's ability to strike Russian targets far from its coast.
While Kyiv's counteroffensive in the south and east has been slowed by minefields and Russian defensive lines, fighting has escalated in the Black Sea region where Russia is imposing a de facto blockade on Ukraine's seaborne exports.
Russian drones have regularly attacked Ukrainian port infrastructure along the Danube River, a vital alternative export route for the major grain producer. It uses its Black Sea Fleet to rain down missiles on Ukrainian targets from afar.
Ukraine's embattled navy has used sea drones to strike back, hitting the Olenegorsky Gornyak landing ship near Russia's naval base at Novorossiysk early last month and a Russian fuel tanker.
'THREE KEY TASKS'
Senior presidential adviser Mykhailo Podolyak said Ukraine was focused on three key tasks aimed at the de-occupation of the peninsula, which lies far behind the battlelines of southern Ukraine.
Kyiv, he said, was targeting air defence systems to open up the path to more strikes on Russian military and warehouse infrastructure. Kyiv was also attacking transport logistics to "stop the large-scale continuous supply of resources and reserves into the area of active hostilities," he said.
"We need to chase away remnants of the Russian Black Sea fleet from Crimean territorial waters and beyond and reinstate the status of the Black Sea as the sea of external jurisdiction," he wrote in English.
Russia regards the peninsula as strategically important and uses its Black Sea Fleet to project power.
Ukraine's military said it had hit Russian air defence systems in a long-range attack in the early hours of Thursday near the town of Yevpatoriya in the west of Crimea, which was seized by Moscow in 2014.
Russia's defence ministry said its air defences shot down 11 drones overnight over the peninsula and did not mention damage.
Footage circulated on social media showed powerful explosions and a plume of smoke rising in the night sky illuminated by a blaze. Reuters could not verify the video.
A Ukrainian intelligence source told Reuters that drones blinded the Russian air defence system by attacking its radar and antenna, and that two Neptune cruise missiles were fired at its launchers.
Reuters was unable to independently verify the account.
(Reporting by Tom Balmforth; Editing by Timothy Heritage and Daniel Wallis)