China on Monday called on the U.S. to reduce its demand for opioids, saying the Trump administration should work to combat the use of the synthetic drug fentanyl, among other drugs.

"It's common knowledge that most new psychoactive substances (NPS) have been designed in laboratories in the United States and Europe, and their deep-processing and consumption also mostly take place there," the deputy chair of China's National Narcotics Control Commission told reporters on Monday, according to CNN.

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"The U.S. should adopt a comprehensive and balanced strategy to reduce and suppress the huge demand in the country for fentanyl and other similar drugs as soon as possible," Liu Yuejin continued. "When fewer and fewer Americans use fentanyl, there would be no market for it."

A congressional report, citing law enforcement, said in 2017 that China was the top source of fentanyl in the U.S.

However, Liu said the U.S. should still be held responsible.

"The U.S. should strengthen its crackdown on distributors, traffickers and drug-related criminal rings," he said. "It should investigate and arrest more lawbreakers."

President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE labeled the opioid crisis as a national public health emergency last year and revealed his plan to combat opioid use in March.

The White House announced earlier this month that it was launching an ad campaign that would work to draw more attention to opioid abuse among young people and warn against its dangers.

Trump also discussed the issue with Chinese President Xi Jinping during his visit to China last year.