PARIS (AP) — France’s Navy, working with intelligence provided by the United Kingdom, on Thursday intercepted an oil tanker in the Mediterranean Sea that traveled from Russia, in a mission targeting the sanctioned Russian shadow fleet, officials said.

French maritime authorities for the Mediterranean said the ship, the Grinch, is suspected of operating with a false flag. The French Navy is escorting the ship to port for more checks, the statement said.

“We are determined to uphold international law and to ensure the effective enforcement of sanctions," French President Emmanuel Macron said in a post about the interception, with a photo showing a French helicopter hovering over a ship.

“The activities of the ‘shadow fleet’ contribute to financing the war of aggression against Ukraine,” Macron added.

The French mission was conducted together with the U.K, which gathered and shared intelligence that enabled the ship to be intercepted, according to French military officials who spoke to The Associated Press on condition of anonymity to discuss the operation.

The ship was flying under a false flag from the Comoros islands, which are off east Africa, and its crew is Indian, the officials said.