Plastic bags of Fentanyl are displayed on a table at the U.S. Customs and Border Protection area at the International Mail Facility at O'Hare International Airport in Chicago
Plastic bags of Fentanyl are displayed on a table at the U.S. Customs and Border Protection area at the International Mail Facility at O'Hare International Airport in Chicago, Illinois, U.S. November 29, 2017. Reuters

Senior U.S. policy makers took aim at China on Wednesday over its approach to Latin America, accusing Beijing of breaching economic norms and urging it to do more to help combat the illegal fentanyl trade.

Testifying before a House of Representatives subcommittee, Brian Nichols, assistant secretary of state for Western Hemisphere Affairs, reiterated the Biden administration's view that China's commercial inroads in the region have been marked by a "lack of transparency" in deals with "strings attached."

Nichols said Latin American countries have grown tired of China's investment tactics, feeling "buyer's remorse," and that the United States needs to provide a viable alternative through diplomacy, foreign aid and private investment.

"It is vital that we answer their call," he said.

The Chinese embassy in Washington did not immediately respond to a request for comment.

Focusing on the fentanyl crisis, Todd Robinson, assistant secretary of state for International Narcotics and Law Enforcement Affairs, testified that most fentanyl seized in the U.S. "is trafficked through Mexico using diverted precursor chemicals sourced from the People's Republic of China."

"We recognize that disrupting the flow of precursor chemicals is crucial," he said.

China has denounced U.S. sanctions on Chinese firms and individuals over their alleged involvement in the fentanyl trade and has accused Washington of trying to deflect blame instead of working to reduce demand for the deadly drug.

Nichols said the U.S. has raised its concerns with China.

"Chinese private companies take the opportunity to sell... chemical precursors to illicit organizations in Mexico which are used to produce fentanyl," he said. "We know that there's more PRC can do in terms of being a better partner in the global community."

Robinson said Washington has provided Mexican authorities with more than 500 drug-sniffing dogs to help detect fentanyl but he added, "We need to get the Mexicans to do more."

Fentanyl is a potent opioid about 50 times stronger than heroin, and has increasingly been mixed with other illicit drugs often with lethal results.

In April, Mexico and the U.S. agreed to ramp up the fight against fentanyl trafficking. Both countries have asked Beijing to help curb the shipment of precursors coming from China, in order to prevent production of the synthetic drug responsible for thousands of deaths in the United States.