SHANGHAI -- Three people were arrested by Shanghai customs on Dec 10, on suspicion of illegally trafficking 3.1 tonnes of pangolin scales, the largest amount ever seized in China.

The scales were concealed in a container registered as carrying timber from Africa, said Shanghai customs on Tuesday.

The main suspect, a native of east China's Zhejiang province, confessed he has been smuggling pangolin scales from Africa to China since 2015.

A pangolin has 0.4 to 0.6 kilogram of scales. The smuggling of 3.1 tonnes of scales means about 5,000 to 7,500 pangolins were killed.

The pangolin is the world's most heavily trafficked mammal. It is under second-class state protection in China and the highest level of protection under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which prohibits international trade of any of the eight pangolin species.

Pangolins are often smuggled into China because their meat is considered a delicacy and their scales are believed to have medicinal qualities.

Those who catch, kill, buy or sell endangered wild animals on the state's protection list can face more than 10 years in prison plus fines.

Further investigation is under way.