A Russian tanker under U.S. sanctions was hit by Ukrainian drone near a strategic bridge in the Kerch Strait that links Russia to the annexed Crimean peninsula, Kremlin officials said Saturday.

The “Sig” was damaged with a hole “near the waterline on the starboard side, presumably as a result of a sea drone attack” Russia’s Federal Agency for Marine and River Transport said in a statement posted to its Telegram channel. There were no casualties, it added.

There was no immediate public claim of responsibility by Kyiv, which usually refrains from taking credit for attacks on Russian soil, but a source in Ukraine’s Security Service, the SBU, told NBC News that it “blew up a large oil tanker of the Russian Federation,” in a joint operation with the navy.

The tanker was “transporting fuel for the Russian troops,” the source said, adding that it was well loaded and “the ‘fireworks’ could be seen from afar.” They said that a surface drone and TNT had been used to carry out the attack. NBC News could not verify their claims.

Video broadcast on Ukrainian television and shared by several officials on social media showed a sea drone moving towards the tanker before striking it. The footage cuts out before an explosion is visible. NBC News was not able to independently verify the footage.

SBU chief Vasyl Malyuk responded to the attack in a Telegram post. “Any explosions that happen with the ships of the Russian Federation or the Crimean bridge is an absolutely logical and effective step in relation to the enemy,” he said.

“If the Russians want the explosions to stop, they should use the only option for this — to leave the territorial waters of Ukraine,” he added.  

Oleksiy Danilov, the secretary of Ukraine’s Security and Defense Council also appeared to reference the attack, which came a day after his country’s security services said they had carried out a drone strike on a Russian navy ship. 

“With each new combat mission, Ukrainian combat UAVs and naval drones become more accurate, operators more experienced, combat coordination more effective, and manufacturers get opportunities to improve tactical and technical characteristics,” he said in a post on Twitter.  

Elsewhere, Vladimir Rogov, a Russian-installed official in Zaporizhzhia in southern Ukraine, said on his Telegram channel that several crew members were slashed by broken glass in the attack. The tanker had been supplying oil to Russian troops in Syria, he said.

Photographs uploaded by Rogov in a separate post showed what he said was the inside of the tanker which had windows blown in, damaged ceilings and office furniture strewn about.

Later, Russia’s Novorossiysk Maritime Rescue Coordination Center was cited by the RIA Novosti news agency as saying that recovery work was underway on the Sig with two tugboats nearby. Water had stopped pouring into the ship, it said. There was no fuel spill as the ship had been carrying only technical ballast, the statement added.

The attack briefly halted traffic on the Crimean Bridge, and ferry transport was suspended for several hours, according to Russian-installed authorities in the area, which Russia illegally annexed from Ukraine in 2014. 

The U.S. sanctioned the tanker and its owner, St. Petersburg-based company Transpetrochart, a marine freight company, for helping to provide jet fuel in Syria in 2019. 

Both Russia and Ukraine have stepped up attacks in the Black Sea since Moscow exited a deal allowing the safe export of Ukrainian grain in July.

On Friday, Ukraine carried out a sea drone strike on a ship near the Russian Black Sea port of Novorossiysk. Russia claimed to have thwarted a wider attack on the port, with drones destroyed by ships guarding the base’s outer boundary. 

But videos circulating online showed the Olenegorsky Gornyak, a Soviet-era warship, being towed back to the port after a Ukrainian intelligence source said it had been damaged in the attack. 

NBC News was able to confirm that videos were filmed in Novorossiysk and showed the same class of warship as the Olenegorsky Gornyak, using marine ship tracking data and satellite imagery.

On Wednesday, Russian drone strikes on the port cities of Odesa and Izmail caused significant damage and fires at facilities key to grain exports.

Odesa, a sea and transport hub and major cultural center, has been hammered by strikes in recent weeks, with dozens of drones and missile attacks targeting sea and river ports.

Ukraine is a major supplier of wheat, corn, vegetable oil and other agricultural products important to the Middle East, Africa and parts of Asia where people are struggling with high food prices and hunger.

Though the nation can also export by road and rail through Europe, those routes are more costly than going by the Black Sea and have stirred divisions among nearby countries.