Customs officers from the Xinjiang Uygur autonomous region have returned more than 200 endangered black pond turtles that had been smuggled into the country from Pakistan.

It is the first time China has sent back smuggled rare animals to their source country.

The animals were handed over to Pakistani officials in the Khunjerab Pass that links the two countries on Monday, and will be set free in a national park near Karachi.

The turtles were smuggled through the Khunjerab land port by a Pakistani businessman on June 13, it is alleged. Customs officers, who had received a tipoff, stopped the suspect's pickup at a checkpoint and found the turtles.

Five suspected buyers from China and a Pakistani middleman were caught later. All are being prosecuted.

Pakistan is one of the main habitats of the black pond turtle. The animal is listed on the Convention on International Trade in Endangered Species and has first-degree national protection status in China.

According to investigators, the turtles can be sold for more than 10,000 yuan ($1,630) each as pets in China.

The return of the turtles is a major step in China's efforts to combat wildlife poaching and smuggling and comes after six metric tons of seized ivory were incinerated in Dongguan, Guangdong province, in January.

"Returning the turtles shows that China is taking on responsibility for stopping the illegal international trade of protected wild animals," Liu Xiaohui, director of the General Administration of China Customs' Anti-Smuggling Bureau, said during the handover ceremony.

Customs officers across China confiscated more than 120 tons of endangered animals and plants during the first seven months of 2014, he added.

cuijia@chinadaily.com.cn