BEIJING (Reuters) - The United States should take action to reduce demand for the drugs fuelling its deadly opioid crisis rather than simply accusing China of being the major source, a top Chinese drug control official said.

“The biggest difficulty China faces in opioid control is that such drugs are in enormous demand in the U.S.,” Yu Haibin of the China National Narcotics Control Commission said at a news briefing, the China Daily reported on Friday.

U.S. President Donald Trump declared the opioid crisis a public health emergency in October and said he discussed with Chinese President Xi Jinping how to “stop the lethal flow” of the drugs during his visit to China last month.

Opioids include prescription painkillers, heroin and fentanyl, a highly addictive synthetic drug 50 to 100 times more potent than morphine.

American law enforcement agencies and drug control experts say most of the fentanyl distributed in the United States, as well as its precursor chemicals, come from China.

While Chinese officials dispute that assertion, the government has taken steps to crack down on the production and export of them, and has placed fentanyl and other related compounds on its list of controlled substances.

Yu said the United States should intensify law enforcement and share more police intelligence with Chinese authorities to combat the problem.

China’s drug control agency said on Thursday that five more precursor chemicals that can be used to produce fentanyl and methamphetamines had been added to its list of controlled substances, the China Daily reported.

Wei Xiaojun, the deputy secretary-general of China’s National Narcotics Commission, said last month that China did not “deny or reject” that some fentanyl produced in China had made its way to the United States but there was not enough evidence to say most of it originated from China.

The U.S. Department of Justice indicted two major Chinese drug traffickers in October on charges of making illegal versions of fentanyl and selling the highly addictive drug to Americans over the internet and through the international mail.