China and the United States will strengthen intelligence sharing and joint investigations to curb fentanyl-related drug crimes, a senior police official said on Friday.

Wei Xiaojun, deputy director of the narcotics control bureau of the Ministry of Public Security, also said that China plans to list two new fentanyl precursor chemicals - 4-ANPP and NPP - as controlled substances. Twenty-three related compounds are already on the control list.

Fentanyl is among a group of new, powerful painkillers collectively known as "novel psychoactive substances" that are either opioids or act like them, and can be 50 to 100 times more potent than morphine. The US Centers for Disease Control said fentanyl resulted in about 20,000 deaths in the country last year.

Wei said that China and US police departments are in contact on some fentanyl trafficking cases and have set up joint investigative teams.

"We're actively sharing intelligence and exchanging information with our US counterparts. Once we have solid evidence, we'll carry out joint actions," he said.

Lance Ho, a senior US narcotics control official, said on Friday that China and the US have made progress in countering cross-border drug-related crimes.

"The two sides will further enhance information exchanges and conduct joint actions to effectively curb such crimes," he said.

According to US media reports, a common way to smuggle fentanyl into the US is purchasing it from Chinese sellers online and then delivering it to the US through international express or logistics companies.

Last week, two Chinese men were charged by US authorities with producing and trafficking fentanyl.

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