France says it has seized an oil tanker in the Mediterranean suspected of being part of Russia's sanction-busting shadow fleet.

French President Emmanuel Macron stated that the tanker, named the Grinch, is subject to international sanctions and suspected of flying a false flag.

The French navy, with assistance from allies including the UK, boarded the vessel on Thursday morning between Spain and Morocco. French maritime authorities reported that a search of the vessel confirmed suspicions regarding the legitimacy of its flag.

Russia's embassy in Paris indicated it had not been informed about the seizure.

Moscow's so-called shadow fleet comprises a clandestine network of tankers used to evade Western sanctions on Russian oil exports, often deploying aged tankers with obscure ownership or insurance.

The Grinch was intercepted while traveling from the Arctic port of Murmansk in northern Russia, according to French authorities. The vessel had been flying a Comoros flag, based on information from ship tracking websites.

President Macron emphasized France's determination to uphold international law and ensure the effective enforcement of sanctions, noting that activities of the shadow fleet contribute to financing Russia's aggression against Ukraine.

The UK Defence Secretary John Healy confirmed that the UK navy provided tracking and monitoring support, with HMS Dagger monitoring the tanker through the Straits of Gibraltar.

Healy stated, Alongside our allies, we are stepping up our response to shadow vessels to choke off the funds that fuel Putin's illegal invasion of Ukraine. The UK has imposed sanctions on 544 Russian shadow fleet vessels.

Ukrainian President Volodymyr Zelensky welcomed the seizure, asserting it was crucial to stop Russian oil from financing the war.

Zelensky suggested that the oil carried by apprehended vessels should be confiscated and sold.

Last October, France seized an additional sanctioned tanker, the Boracay, off its west coast, later releasing it shortly after.

Shadow fleets are increasingly common, with countries like Venezuela, Iran, and Russia accused of using them to bypass sanctions. Financial intelligence firm S&P Global estimates that one in five oil tankers globally is used for smuggling oil from sanctioned countries.