The French authorities on Saturday reported that a Russian ship has been suspected of violating trade sanctions agreed by the European Union (EU) against Russia.

The Russian-flagged Baltic Leader, which had set sail from the French city of Rouen, was escorted to the port of Boulogne-sur-Mer by French forces, the maritime prefecture told Agence France-Presse (AFP). It is suspected of belonging to a company targeted by EU sanctions against Moscow, it added.

It was stopped by a French customs patrol vessel backed by a police surveillance ship and a patrol boat of the navy, said Veronique Magnin of the regional prefecture.

The 127-meters (417-foot) vessel is "strongly suspected of being linked to Russian interests targeted by sanctions," she said, adding that while such a measure was "rare" as it is "a sign of "firmness."

The move comes after the EU Thursday adopted unprecedented sanctions against Russian individuals, companies and other entities to punish Moscow for its invasion of Ukraine.