French soldiers have boarded an oil tanker believed to be part of Russia's shadow fleet, used to evade sanctions imposed because of the war in Ukraine.
The Boracay left Russia last month and was off the coast of Denmark when unidentified drones forced the temporary closure of several airports last week. It has been anchored off western France for a few days.
French President Emmanuel Macron said at an EU leaders' summit in Copenhagen on Wednesday that the crew had committed serious offences, but did not elaborate.
Kremlin spokesman Dmitry Peskov stated that Russia had no knowledge of the vessel.
French military personnel reportedly boarded the vessel on Saturday. Macron refused to comment on whether the ship may have been used as a platform for the drone flights that caused disruption in Denmark.
Prosecutors in Brest have initiated an investigation on two counts: refusing an order to stop and failing to justify the nationality of the ship's flag.
Many Western countries have imposed sanctions on Russian energy by limiting imports and capping prices following the start of Russia's full-scale invasion of Ukraine in 2022. To evade these sanctions, Moscow has established a shadow fleet of tankers whose ownership and operations are less transparent.
Reports suggest that Russia operates several hundred tankers registered under various flags to export its oil surreptitiously. Macron indicated that this shadow fleet may comprise between 600 and 1,000 vessels.
The Boracay is registered under Benin's flag but is included in UK and EU sanctions against Russia. Earlier this year, it was detained by Estonian authorities for sailing without a valid flag.
Having departed from the Russian port of Primorsk, the Boracay's intended route was supposed to lead to Vadinar in north-western India by 20 October. However, after being shadowed by a French warship, it altered course toward the French coast.
During the EU leaders' meeting, Danish Prime Minister Mette Frederiksen expressed concerns about Russian threats emphasizing the need for a robust response, underscoring the broader regional security implications of such incursions.
Authorities are concerned about potential hybrid threats following drone activities over Danish airspace, though no evidence directly linking Russia to the recent disturbances has yet emerged.