States should act to prevent ‘furtive’ ship-to-ship oil transfers up to 370km from their coastlines if poor oversight of tanker activities increases the risk of oil spills, according to a paper submitted to the International Maritime Organization.

The document is the latest effort by states, including Spain and Denmark, to increase scrutiny of STS oil transfer operations off European shores following Russia’s invasion of Ukraine and the subsequent economic sanctions.

European states have been alarmed by the rise of ship-to-ship operations in the Mediterranean Sea involving tankers that have loaded from Russian ports and then transferred oil to VLCCs that head to Asia.