Ukrainian sea drones attacked the Russian Black Sea port of Novorossiysk, a major hub for Russian exports, early on Friday and were destroyed by Russian warships, Moscow's Defence Ministry has said.
The attack prompted the Novorossiysk port to halt all ship movement, according to the Caspian Pipeline Consortium that operates an oil terminal there, Reuters reported.
Explosions and gunfire were heard near Novorossiysk on Friday morning, Russian social media users reported.
It would be the first Ukrainian attack on one of Russia's main commercial ports, if confirmed.
Videos posted in a local online community and circulated by Russian online news outlet Astra showed the movement of ships just off the coast with the sound of gunfire coming from the direction of the sea.
The emergency services of Novorossiysk have confirmed reports of blasts and security services have been informed, Russia's RIA news agency reported.
The port is one of the biggest in the Black Sea.
Clashes in the Black Sea and adjacent ports have escalated since Russia refused last month to extend a deal allowing for the safe exports of grain from Ukrainian ports.
Russian drones and missiles have struck several Ukrainian port facilities and grain silos on or near the Black Sea.
Russia has also reported an attack by Ukrainian sea drones on its warships, which were escorting a civilian vessel.
The development comes as US Secretary of State Antony Blinken called on the UN Security Council on Thursday to urge Russia to stop using the Black Sea as “blackmail”, following Moscow's recent exit from a deal that allowed for the safe export of Ukrainian grain.
“Every member of the United Nations should tell Moscow enough … Enough using the Black Sea as blackmail,” Mr Blinken told the 15-member council in New York.
“Enough treating the world's most vulnerable people as leverage. Enough of this unjustified unconscionable war.”
Mr Blinken, who was heading a high-level meeting on conflict-induced global food insecurity, said grain prices had risen “by more than 8 per cent around the world” since Russia’s withdrawal from the deal.
The termination of the agreement has had a significant impact on the Global South.
Mr Blinken added all possibilities were being explored to optimise the export of grain from Ukraine by land, sea, rail and river, but said it would remain challenging to replicate the success achieved through the Black Sea grain deal.
Mr Blinken added all possibilities were being explored to optimise the export of grain from Ukraine by land, sea, rail and river, but it would remain
