On Tuesday, the French navy boarded the oil tanker Deliver as it passed off the coast of Sicily in violation of the law of the sea, Macron said.
Macron links the ship to the so-called shadow fleet that Russia uses to circumvent international sanctions. The fleet consists of hundreds of cargo ships of varying seaworthiness that sail under so-called flags of convenience.
Maritime traffic sites showed on Thursday morning that Deliver was located just east of Malta.
The 274-meter-long ship sails under the Cameroonian flag and is en route from Russia's largest oil port, Primorsk, to Singapore.
