The Kremlin has slammed the seizure of a tanker in the Atlantic by France and other navies as "illegal", comparing the move to "piracy" after Paris said the vessel was violating sanctions.
"We consider these acts as illegal, they border on international piracy," Kremlin spokesman Dmitry Peskov said, adding that "Russia is taking measures to ensure the safety of its cargo."
The Russian captain of the tanker refused to comply with the French navy's orders, and "taking control of the vessel proved necessary", a French prosecutor said.
Posting on X, French President Emmanuel Macron said; "the French Navy intercepted a new tanker under international sanctions yesterday morning, originating from Russia: the Tagor.
"Our determination is steadfast and unwavering. This operation was carried out in the Atlantic, in international waters, with the support of several partners including the United Kingdom, in strict compliance with the law of the sea.
"It is unacceptable for ships to circumvent international sanctions, violate the law of the sea, and fund the war that Russia has been waging against Ukraine for more than 4 years.
"These vessels, which fail to adhere to the most basic rules of maritime navigation, also pose a threat to the environment and to everyone's safety."
Footage accompanying the post showed French troops rappelling on to the ship's deck from a helicopter, as well as night vision footage of armed troops walking along a gangway aboard the vessel.
Oil tanker with ties to Iranian magnate
Suspected of carrying Russian or Iranian oil despite international sanctions, the Tagor is linked to petroleum shipping magnate Mohammad Hossein Shamkhani, according to open-source database Opensanctions.org.
According to French authorities, the Tagor was on its way from Murmansk in northwestern Russia when it was boarded.
The ship was falsely flying a Cameroonian flag and was heading toward Limbe, a seaside city in the west of the African country, said a spokesperson for France's Atlantic maritime prefecture.
The Atlantic maritime prefecture said the interception had taken place more than 400 nautical miles (740km) west of Brittany.
"The examination of the documents confirmed doubts about the irregularity of the flag being flown," the prefecture said.
The ship, which had 23 crew members, was "being escorted by the French navy to an anchorage point for further checks", the prefecture said.
When asked about the tanker's ties to Mr Shamkhani, officials declined to comment.
Mr Shamkhani is the son of security official Ali Shamkhani, who was an adviser to the former Iranian supreme leader Ali Khamenei, both of whom were killed on 28 February, the first day of the US-Israeli attacks that started the Middle East war.
The Russian embassy in France said it had requested information from the French authorities about the makeup of the crew.
"No notifications have been provided by the French side regarding actions taken against this vessel," the embassy said on its Telegram channel.
The tanker has flown the flags of Madagascar, the Marshall Islands and Panama.
Prosecutors said that "taking control of the vessel proved necessary".
The prosecutor's office in the northwestern city of Brest said a criminal investigation had been opened over failure to prove a vessel's nationality, absence of a flag and refusal to comply.
"It is a vessel that was known and tracked," Guillaume Le Rasle, spokesman for the Atlantic maritime prefecture, told AFP, adding that the vessel was under EU and US sanctions.
"The decision to divert it was taken Sunday evening," he added. "The objective of the diversion is to verify the validity of its flag."
It is the latest in a string of actions by western nations to frustrate Moscow's so-called shadow fleet, the network of tankers used to export goods out of Russia and evade sanctions placed on the country after its full-scale invasion of Ukraine.
The shadow fleet vessels frequently change the flags they fly, a practice known as flag-hopping, or use invalid registrations in an attempt to escape tracking.
The three other ships France has detained since September on suspicion of belonging to the shadow fleet were allowed to sail after their owners paid fines.
In April, France announced a plan to double penalties for ships that fail to fly a flag or refuse to comply.
Several Western countries have imposed sanctions on hundreds of vessels in Russia's shadow fleet over its 2022 invasion of Ukraine.
Nearly 600 ships suspected of belonging to the fleet are subject to European Union sanctions.
The UK and France have both vowed to prevent Russian flagged ships passing through their waters.
UK Prime Minister Keir Starmer in March gave permission for British forces to seize shadow fleet vessels, leading the ships to veer way from the English Channel.
At the start of the year, the UK assisted the US in capturing the Marinera, a Russian-linked tanker travelling across the Atlantic from Venezuela.
It also helped the French capture a Russian oil tanker called the Grinch in the Mediterranean.
Additional reporting: PA
