A sea drone attack damaged a Russian tanker near the strategic bridge linking Russia to the annexed peninsula of Crimea, Russian authorities said on Saturday.
Russian media said the SIG vessel, approaching the Kerch Strait linking the Black Sea and the Sea of Azov, was hit by Ukrainian drones. Ukraine's Interfax agency, citing an unnamed Ukrainian security service source, also said Ukraine's navy was behind the attack with drones in its territorial waters.
Reuters could not immediately verify the reports.
No one was hurt, but the Crimean Bridge and ferry transport were suspended for several hours, according to Russian-installed officials in Crimea, which Moscow seized from Ukraine in 2014.
Kyiv seldom claims responsibility for attacks inside Russia or on Russian-controlled territory in Ukraine, but has said that destroying Russia's military infrastructure boosts its counteroffensive chances in the 17-month-old war.
A drone attack on Russia's navy base at Novorossiysk damaged a Russian warship on Friday, the first time the Ukrainian navy has projected its power so far from its shores.
The SIG had been supplying oil to Russian troops in Syria, according to Vladimir Rogov, a Russian-appointed official in Ukraine's southeastern region of Zaporizhzhia.
The United States sanctioned the tanker and its owner, St. Petersburg-based Transpetrochart, in 2019 for helping provide jet fuel in Syria.
Rogov posted on Telegram an audio clip in which the SIG requested a tow from tugboats. He also posted pictures of what he described as shattered fixtures and equipment inside the vessel.
"The SIG tanker... received a hole in the engine room near the waterline on the starboard side, preliminarily as a result of a sea drone attack," Russia's Federal Marine and River Transport agency said in a statement on Telegram.
Russia's Novorossiysk Maritime Rescue Coordination Center was cited by the RIA news agency as saying that water had stopped pouring into the SIG and that recovery work was underway with two tugboats nearby.
There was no fuel spill, it added, as the ship had been carrying only technical ballast.
The Moscow-installed authorities in Crimea said the bridge, which was completed by Russia in 2018 and has come under serious attack twice in the war, was not targeted.
Ukraine's UNIAN news agency said three explosions had been reported in the area. There was no immediate comment on the incident from Ukraine's government.