On October 1, the French military boarded a ship carrying Boracay oil, which was suspected of belonging to the "dark fleet" carrying Russian oil, when the ship anchored near the port city of Saint-Nazaire on the west coast of France.
An official investigation was opened after the crew failed to provide documents proving their nationality and refused to comply with orders from authorities.
A group of French soldiers had been on the ship since September 27. Meanwhile, the French Navy and coastguard declined to comment on the incident.
Speaking at the European Union summit in Denmark, President Emmanuel Macron called it a positive signal and affirmed that France needed to clarify any violations involving unclear oil tankers. He said that Russia's "shadow fleet" could include between 600 and 1,000 ships worldwide.
Ship owners in the "shadow fleet" often have vague ownership rights and are not transparent about insurance, most of which are over 20 years old. This is a method that Russia is accused of using to circumvent Western oil sanctions after the Ukraine conflict.
The Boracay ship was arrested by Estonian authorities earlier this year while operating without a valid national flag.
Maritime data shows that the ship left the port of Primorsk (Russia) on September 20, passed through the Baltic Sea, passed through Denmark, and then entered the Strait of Manche before reaching French waters. During this journey, it was closely followed by a French warship.
Russia has said it has not reported any information about Boracay, but Kremlin spokesman Dmitry Peskov said that sometimes Russia has to take action to " restore order" when other countries carry out "provocational actions".
The Boracay ship is on the list of sanctions imposed by the UK and the European Union against Russia. If the violation is proven, the ship could be confiscated or banned from operating in European ports.
The incident is sparking controversy as Europe has tightened control of oil transportation, as Russia tries to maintain revenue from energy exports.
