Customs officials in China have seized 2,674 pangolin carcasses in the biggest trafficking case involving the species in five years. Authorities intercepted the haul on a fishing boat in September.

They found thousands of dead pangolin stuffed inside 414 cool boxes weighing 11.5 tonnes, China's Xinhua news agency reported. Two suspects on the boat were arrested. They later told police they would get 10,000 yuan (£1,000, $1,540) if they delivered them to their final destination.

It is illegal to catch, kill or buy endangered wild animals in China and those found guilty face over 10 years in jail and fines. Pangolins, commonly known as scaly anteaters, are protected under Chinese law.

They are often smuggled for their meat, which is considered a delicacy, and for their scales, which are believed to have medicinal properties. The scales are made from keratin – the same structural material that makes up fingernails and the outside layer of human skin.

There are eight species of pangolin living today. Two of these – the Sunda pangolin and the Chinese pangolin – are considered critically endangered. Indian and Philippine pangolins are listed as endangered, while the remaining four (black-bellied, white-bellied, giant ground and Temminck's ground pangolin) are vulnerable.

Increased demand over recent years has led to prices of their body parts surging from £8 per kg of scales in the 1990s to £324 today. Researchers from the International Home for Conservation of Nature (IUCN) say more than a million pangolins have been caught over the last 10 years, making them the most illegally traded endangered mammal on the planet.