Several magnetic mines had been detected on a tanker in Russia's Baltic Sea port of Ust-Luga, Russia's Investigative Committee said on Monday.
The committee said the mines, manufactured in a NATO country, were found by divers during an inspection of the hull of the tanker Arrhenius, which arrived from Belgium's port of Antwerp to load liquefied petroleum gas.
Russia has beefed up safety measures in its ports following suspected acts of sabotage aimed at undermining its energy infrastructure.
NATO has not mined any tanker, a NATO official said in an emailed statement.
Last year, Russia ordered divers to inspect ships in its ports, after suspected attacks on four oil tankers. The Suezmax tanker Koala ran aground at Ust-Luga after a blast in its engine room in February 2025.
According to LSEG ship tracking data, Arrhenius is Liberia- flagged and is managed by the Maple Mariner Holding in the UAE.
A spokesperson for Russia's Investigative Committee, Svetlana Petrenko, said that the mines were produced by a NATO country. She said the vessel, which entered Ust-Luga on May 20, was scheduled to sail to the Turkish port of Samsun.
The mines were deactivated, she said.
"Based on initial investigative actions, it can already be concluded that the magnetic mines could not have been installed in Russia's territorial waters," Petrenko said.
(Reuters - Reporting by Reuters, Writing by Alessandra Prentice, additional reporting by Inti Landauro; editing by Guy Faulconbridge and Ros Russell)
