WASHINGTON: The US Treasury named four individuals and one company as important figures in a leading Chinese fentanyl manufacturing and trafficking group, boosting pressure on China to take action against it. The Treasury said Songyan Ji, Longbao Zhang, Guifeng Cheng, and Guangfu Zheng, and Global United Biotechnology Inc. were all part of the Shanghai-based Zheng Drug Trafficking Organization of Fujing Zheng, who was indicted by the Justice department in 2018.

Zheng's gang, according to the Treasury, has produced and shipped large amounts of deadly synthetic opioids like fentanyl and carfentanil, which is 100 times more potent than fentanyl, to the United States where they fuel an epidemic of addiction and overdoses.

The four Chinese named Friday to the Treasury sanctions blacklist have been instrumental in facilitating payments for the Zheng group, it said. Global United Biotechnology is run by Zheng as "a virtual storefront" for the trafficking group, which processes payments using virtual currencies like bitcoin to launder proceeds through China and Hong Kong-based companies, it said.

The Treasury did not say whether China, amid deteriorating relations with the United States, has taken action against the group. "Fujing Zheng remains in China," it said in a statement.