A court in the southern city of Guangzhou handed long-term prison sentences to 17 people, including two for life, for running China’s largest ivory smuggling ring. The ring used to move millions of dollars of tusks from West Africa into the mainland’s vast domestic market, reported news agency AFP.

Demand for ivory carvings and jewellery among China’s expanding middle class led to poaching crisis across Africa, and although a 2018 ban on ivory trade in China has improved the situation, a vast black market still exists.

The people sentenced were involved in smuggling over 20 tons of ivory worth more than 1 billion yuan ($156 million).

The illicit haul was brought from Nigeria and other unnamed countries and shipped to China through Singapore and South Korea, court documents published by the Guangzhou Intermediate People’s Court revealed.

The document described the case as the “biggest ivory smuggling racket” since the foundation of the People’s Republic of China seventy years ago.

Two men identified as “ring leaders” — Chen Chengzong and Lin Zhiyong — were jailed for life and stripped of their property, in what activists say is one of the toughest sentences to date for ivory smuggling.

Chen was found guilty of purchasing, selling and transporting rare animal products. The court said he had used fake passports to cross the Chinese border 21 times.

“Under China’s Criminal Law, individuals found guilty of smuggling rare animal products are usually given a five- to ten-year prison sentence,” Li Zongsheng, a lawyer who has campaigned for tougher wildlife protection laws, said.

“The two life sentences given in this case is quite unusual, indicating authorities are coming down hard on illegal ivory traders.”

Fifteen others were given sentences ranging from two to 15 years. The group had also smuggled and sold rare rhino horns.

More than 20,000 elephants were killed annually for their tusks prior to the 2018 ban, according to the World Wildlife Fund (WWF).