The Liberian-flagged Aframax Rio was struck near Sochi after Kiev threatened to intensify attacks on Russia's energy industry

A Liberian-flagged oil tanker has caught fire off Russia's Black Sea coast after being attacked by unmanned boats near Sochi, the Russian Transport Ministry has said. All 23 members of its crew, who are Indian nationals, were rescued and no injuries have been reported.

The Aframax Rio, which was carrying crude oil, was struck by sea drones on Tuesday, according to the ministry. The attack triggered an oil fire in the Black Sea, with emergency crews initially unable to approach the tanker because of the intensity of the blaze.

Russian Transport Minister Andrey Nikitin convened an emergency response headquarters, while the ministry said sufficient personnel and equipment had been deployed to deal with the consequences.

Authorities temporarily closed beaches in the nearby federal territory of Sirius as a precaution. Local officials said subsequent monitoring found pollutant concentrations below permitted limits and that there was no immediate danger to public health.

In a separate incident on Tuesday, two merchant vessels were struck by unidentified naval and aerial drones in Bulgaria's exclusive economic zone, some 128km off its coast. The Togo-flagged Alfa Watan suffered critical damage and sank, while the Palau-flagged Able caught fire. Eighteen crew members were rescued from the latter vessel, two of them with severe injuries.

Bulgarian Prime Minister Rumen Radev condemned the attacks as a "blatant violation of international law and maritime law" and warned that repeated strikes were disrupting Black Sea shipping and driving insurance costs higher.

Kiev has not publicly claimed responsibility for the strikes. Ukraine has, however, sharply expanded attacks on Russian oil infrastructure and commercial shipping in the Black Sea and Sea of Azov in recent months, using combinations of naval and aerial drones to strike vessels linked to Russian ports.

Ukraine's Vladimir Zelensky vowed over the weekend to intensify attacks on Russian oil refineries, prompting Moscow to announce that it would expand strikes on Ukrainian military-industrial facilities and related infrastructure. Moscow has already been targeting vessels it says are carrying military or dual-use cargo to Ukrainian Black Sea ports, while the Russian Defense Ministry said Zelensky would bear "full personal and political responsibility" for any further escalation.

The strikes have also become a factor in the global fuel market. US President Donald Trump said on Monday that rising American gasoline prices were now being driven less by disruption around the Strait of Hormuz and more by Ukrainian attacks on Russian refineries.

"What's driving up gasoline is no longer the Strait of Hormuz," Trump wrote, arguing instead that Russian refineries "are being blown up by Ukraine."

Trump had previously urged Zelensky to "stop knocking out diesel fuel in Russia," saying the campaign was "hurting the world." US Treasury Secretary Scott Bessent has similarly said Ukrainian attacks on Russian energy assets and refined products are contributing to a broader "energy shock."