Part of the investigation will look into whether the Boracay was used as a launchpad for a drone incursion into Denmark’s airspace last week which forced the closure of its airports.
France has launched an investigation into a Russian-linked oil tanker for "serious offences," President Emmanuel Macron said on Wednesday.
Authorities have opened a probe into the Benin-flagged Boracay vessel, which is named on a list of shadow fleet ships and subject to EU sanctions.
"There were some very serious offences committed by this crew, which justify the current judicial procedure," Macron said at an EU leaders' defence summit in Denmark.
Part of the investigation will look into whether the Boracay was used as a launchpad for a drone incursion into Denmark's airspace last week which forced the closure of its airports.
Macron however stopped short of confirming reports of a link to the tanker and the airspace violations, saying he would "remain very careful."
Built in 2007 and known as Pushpa and Kiwala, the Boracay is currently anchored off Saint-Nazaire in western France.
The EU has sanctioned hundreds of tankers used by Russia to bypass sanctions on its oil exports since its 2022 full-scale invasion of Ukraine.
The so-called shadow fleet are aging vessels with obscure ownership and operating without Western-regulated insurance.
Russia's use of the vessels has also raised environmental concerns about accidents given their age and uncertain insurance coverage.
The Boracay was blacklisted in February under its previous name, Kiwala.
The tanker left the Russian port of Primorsk outside Saint Petersburg on 20 September and was due to arrive at the port of Vadinar in India on 20 October, according to data from the Marine Traffic website.