Russia's transport ministry on Wednesday accused Ukrainian naval drones of attacking a Russian liquefied natural gas carrier, the Arctic Metagaz, which caught fire in the Mediterranean a day earlier.
If confirmed, it would be the first time that Ukraine has attacked a Russian LNG carrier.
The Security Service of Ukraine did not respond to a request for comment.
Ukraine has frequently targeted Russian oil refineries and other energy infrastructure in an attempt to deprive Russia's war machine of funding.
Russia's transport ministry said all 30 crew members, who were Russian nationals, were safe.
"We qualify what happened as an act of international terrorism and maritime piracy, a gross violation of the fundamental norms of international maritime law," Reuters quoted the ministry as saying in a statement.
It said the vessel, which had been carrying a cargo from the Russian Arctic port of Murmansk, was attacked near international waters belonging to Malta and thanked Maltese rescue services.
Ukrainian naval drones had launched their attack from the coast of Libya, the ministry said.
The vessel's Russia-based manager LLC SMP Techmanagement and Russia's largest LNG producer Novatek have not yet commented on the incident.
