Shanghai authorities seize a total of 1.1 tons of cocaine concealed in the cargo of frozen mackerel.[Provided to chinadaily.com.cn]

Under a cooperative program between Chinese and United States customs, Shanghai authorities seized 1.1 tons of cocaine concealed in the cargo of frozen mackerel at Yangshan Deepwater Port on Nov 4, 2016, custom officials announced at a news conference on Thursday.

Officials said this was the largest bust of the drug in China in recent years.

The cargo, which was declared as 20 tons of frozen Pacific mackerel, was headed to Cambodia from South America. According to custom officials, the cocaine was divided into 1,102 packets and hidden at the bottom of the cases of mackerel. The packets were marked with special transparent sealing tape.

The authorities extracted the cocaine and placed the fish back in their cases before allowing the ship to proceed as scheduled. Chinese and Cambodian police later caught a suspect, identified as a Vietnam national, when he attempted to receive the cargo on Nov 26.

Police said they are still on the hunt for three more suspects, including another Vietnamese and two Vietnamese Canadians.

He Qi in Shanghai contributed to this story.