Qingzhou Wang, 37, principal executive of Amarvel Biotech, a company based in Wuhan, and Yiyi Chen, 33, the firm's marketing manager, were convicted in New York in February of fentanyl precusor importation and money laundering.

District Judge Paul Gardephe sentenced Wang to 25 years in prison on Friday. Chen was sentenced to 15 years in prison on August 22.

"These executives turned a Chinese chemical company into a pipeline of poison, shipping hundreds of kilos of fentanyl-related precursors into the United States, disguising them as everyday goods, and cashing in through cryptocurrency," Drug Enforcement Administration chief Terrance Cole said in a statement.

Wang and Chen were among eight Chinese nationals and four Chinese companies charged by the Justice Department in June 2023 with trafficking fentanyl precursor chemicals into the United States.

It was the first time the United States had charged Chinese companies for trafficking fentanyl precursor chemicals inside the United States, rather than shipping them to Mexico, the origin of most of the fentanyl found in the country.

Fentanyl is a synthetic opioid that is 50 times more powerful than heroin and much easier and cheaper to produce. It has largely replaced heroin and prescription opioids like oxycodone as a cause of overdoses in the United States.

The June 2023 indictment of the Chinese executives and companies drew protests from Beijing.

"It is completely illegal and seriously damages the basic human rights of Chinese citizens and Chinese companies," the Chinese foreign ministry said at the time. "China strongly condemns this."

Although Mexico has been the main source of fentanyl sold in the United States, Washington has increasingly focused its attention on China-based suppliers of ingredients.