Illegal shark finning persists undetected because of loopholes in European Union regulations, a report by a conservation group says.

Finning is taking off a shark's fins and throwing the rest of the carcass back into the sea, a practice that the EU has regulated since 2003, the BBC reported Thursday.

Shark finning is banned in the EU but under present rules member states may issue special permits to exempt fishing vessels from the finning-at-sea prohibition.

Marine experts are calling for a halt to the special permits that allow fishermen to remove fins at sea.

"The waste and unsustainable mortality associated with finning pose threats to shark populations, fisheries, food security and the sustainability of marine ecosystems," Sonja Fordham of the International Union for Conservation of Nature's Shark Specialist Group, said. "The most reliable way to enforce a shark-finning prohibition is to require that sharks be landed with their fins naturally attached to their bodies.

"This method is being mandated for more and more fisheries, particularly in Central and North America, creating momentum for global change," she said.

Shark fins are prized and command high prices for use in shark fin soup, an expensive, traditional, celebratory Chinese dish.

In contrast, shark meat is cheap, hard to store and takes up a lot of storage space. Finning at sea allows vessels to harvest the valuable asset while the remaining carcass is dumped.