A critically endangered porpoise has been found dead in a Chinese lake after apparently being slashed on the belly and strapped to two bricks.

It is believed that the Yangtze finless porpoise, a protected aquatic species, was dumped into water with the slabs and left to die, according to conservationists who found its corpse.

The mammal belonged to an extremely rare freshwater species. Only around 1,000 of them - less than the population of the giant panda - live on Earth, and all of them are in China's Yangtze River.

The Yangtze finless porpoise was pulled up from Dongting Lake in southern China this morning

Animal conservationists found a seven-inch-long slash wound on its belly and two bricks firmly bound to its tail by a rope. The authority is examining the body and investigating the case

The body of the porpoise was discovered this morning in Dongting Lake in southern part of the country.

Workers from East Dongting Lake Ecological Protection Association spotted the dead mammal and removed it from the water after being notified of its existence by passing fishermen.

The male porpoise weighed 43 kilograms (94.8 pounds) and measured 1.52 metres (4ft11in) in length, according to a post from the charity organisation. Its body was found to be slightly decayed.

The body of the animal was discovered by the animal charity after it was notified by fishermen

The charity has condemned the person who abused the animal and dumped it into the lake

Its belly had an 18-centimetre-long (seven-inch-long) slash wound, the group said.

'What is most infuriating is that a nylon rope had been tightly bound to the porpoise tail and two bricks were strapped to the rope. What was the purpose of such cruel method?' the charity wrote.

The porpoise's corpse has been handed to the local fishery authority, which is investigating the matter.

Different from dolphins, porpoises have shorter snouts, smaller mouths, less curved dorsal fins and shorter, chubbier bodies.

Finless porpoises are characterised by the lack of dorsal fins; instead, they have wider dorsal 'grooves'.

They can be found along the coast of eastern and southern China. However, Yangtze finless porpoises, which is a sub-species, only live in China's longest river.

Yangtze finless porpoise, native to China, are known for their mischievous 'smiles' (file photo)

According to statistics from last year, there are around 1,012 Yangtze finless porpoises in the world and among them, 200 live in Dongting, the second largest freshwater lake in China.

They are known for their mischievous 'smiles', and have a level of intelligence comparable to that of gorillas, according to WWF, which labels the species critically endangered.

All porpoises are subjected to trade controls by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Hunting, killing and trading of finless porpoises are prohibited by the Wild Animal Conservation Law.