The U.S. accusation that China has failed to honor its promises to stop sales of the synthetic opioid fentanyl to the United States is completely inconsistent with the facts and China cannot accept it, a senior official said on Saturday. 

Liu Yuejin, deputy director of the China National Narcotic Control Commission, told CCTV in an interview that in fact, China has taken more severe control measures on fentanyl substances than the United States. 

U.S. President Donald Trump made the groundless accusations on Thursday on his Twitter.

Read more: Infographic: Why is fentanyl dangerous?

In April, China added all fentanyl-related substances to a supplementary list of controlled narcotic drugs and psychotropic substances with non-medical use in China, effective since May 1. 

The restrictions include 25 fentanyl derivatives, four more than the United Nations have in place, which means all fentanyl substances are strictly controlled in China. 

Read More: Fighting fentanyl abuse: China's new restrictions on synthetic opioid 

On Friday, Chinese foreign ministry spokesperson Hua Chunying also refuted the accusation. "The root cause of the fentanyl issue in the United States does not lie with China. To solve the problem, the United States should look harder for the root of the problem at home," Hua said. 

"China always honors its pledges," Hua said after a daily press briefing when asked to comment on Trump's post on Twitter. 

Hua said the scheduling of fentanyl-related substances is an important move taken by the Chinese government to ward off the risk and potential harm of new-type drugs. It is good for our people's well-being and also part of global drug control to safeguard security and stability of the world. "The root cause of the fentanyl issue in the U.S. does not lie with China. To solve the problem, the U.S. should look harder for the cause at home," she added.