The U.S. Office of Foreign Assets Control (OFAC), a division of the Treasury Department, sanctioned four Chinese nationals for allegedly using cryptocurrency to launder proceeds from illicit drug transactions.

In a press release Friday, OFAC said Songyan Ji, Longbao Zhang, Guifeng Cheng and Guangfu Zheng, as well as Global Biotechnology Inc., provided support to the Zheng Drug Trafficking Organization under the Foreign Narcotics Kingpin Act.

Zheng DTO was also listed in a previous sanctions effort by OFAC, when the division added Xiaobing Yan, Fujing Zheng and Guanghua Zheng to its Specially Designated Nationals (SDN) list as narcotics traffickers last August.

"The Zheng DTO laundered its drug proceeds in part by using digital currency such as bitcoin, transmitted drug proceeds into and out of bank accounts in China and Hong Kong, and bypassed currency restrictions and reporting requirements," the release said.

Unlike last August's action, no bitcoin or other crypto addresses were added to the sanctions list. The release also did not indicate the magnitude of the alleged laundering.

OFAC's action means it is attempting to seize all property belonging to the individuals in the U.S., and U.S. entities are now prohibited from dealing or transacting with the four designees.

Friday's action is only the third time cryptocurrency has come up in an OFAC sanctions update. The agency first indicated it would add crypto addresses to its sanctions list in March 2018, saying crypto would be treated identically to fiat currencies as far as the SDN list was concerned.

The SDN list is OFAC's blacklist for individuals or entities who the agency believes has violated U.S. law.

In addition to last August's actions, OFAC has also sanctioned two Iranian residents it claimed were involved in laundering funds from the SamSam ransomware, which impacted government agencies and private entities.

That action, in 2018, marked the first time bitcoin addresses appeared on the SDN list.