Dutch authorities are cracking down on shadow fleet tankers using fraudulent Caribbean flags linked to the Netherlands Antilles, reported Fort Lauderdale's Maritime Executive.

The Royal Association of Netherlands Shipowners (KVNR) says dozens of tankers routinely fly the flags of Aruba, Sint Maarten and Curacao, despite the fact that Aruba and Sint Maarten do not operate registries. Curacao, which does, has not registered any of the implicated vessels.

KVNR warned that the use of fake flags damages the reputations of the Netherlands and Curacao. It urged enforcement within Dutch waters and noted that international law may permit action against stateless ships even on the high seas.

Curacao officials called for foreign port state control authorities to act against tankers falsely flying its flag and to pursue criminal charges. According to the Curacao Chronicle, the Dutch government is actively challenging fraudulent registrations.

Dutch coast guard assets intercepted two vessels flying Aruban flags in the Dutch EEZ in August but did not board them. Inspections of suspect vessels are expected when they anchor in Dutch waters, the Chronicle reported.

The shadow fleet has grown rapidly due to Western sanctions on Russia, shifting to less-legitimate flag states as major registries avoid compliance risks. Including sub-fleets serving Iran and Venezuela, the fleet may number up to 900 vessels, or 17 per cent of global tanker tonnage, according to S&P Global. Most are ageing and underinsured.