Vienna, Austria - The US and China traded blows on Monday after Washington accused Beijing of allowing the sale of fentanyl precursor chemicals during a UN Commission on Narcotic Drugs meeting.

"We know where ​the chemical [fentanyl] precursors are coming from," White House Office of National Drug Control Policy director Sara Carter told the UNCND in Vienna. "They are manufactured by ⁠the millions of tons in China."

Her comments came as part of the US official's statement to the UNCND's annual meeting on Monday, triggering an angry response from Beijing.

"We know that ​China's weak export controls and lax enforcement allow its chemical industry to foster friendships with the cartels," Carter told the gathering, according to Reuters.

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"At the same time, China's overly effective controls over rare earth minerals wreak havoc on legitimate ​industries," she claimed.

The issue of fentanyl precursor chemicals has become a sore point for US-Chinese relations, especially under President Donald Trump's second administration, which has cited the issue as a major trigger for Washington's unpredictable tariff policy.

Former President Joe Biden worked closely with China and with Beijing's assistance launched a wide-ranging crackdown on the trade of fentanyl precursors. He also created a bipartisan anti-fentanyl working group.

China responded fiercely to Carter's accusations on Monday, stating that the US should improve its control measures, not use sanctions and tariffs to coerce its way into getting what it wants.

"A certain country using the drug problem as a pretext has resorted to unilateral bullying ​and even interfered in the internal affairs of other countries," Chinese UN envoy Gao Wei said in a statement. ​

"It is regrettable that just now the US delegate again made ⁠remarks ​that do not reflect reality," Gao said.