The US Treasury Department's Office of Foreign Assets Control (OFAC) said it also targeted an individual and two entities for "facilitating North Korean illicit financial activity."

"The United States will continue to enforce UN and US sanctions and shut down illicit revenue streams to North Korea," Treasury Secretary Steven Mnuchin said in a statement.

"Our sanctions will remain in place until we have achieved the final, fully-verified denuclearization of North Korea."

The sanctions freeze any property or assets on US soil held by the designated entities, and bar US citizens from doing business with them.

OFAC said it imposed sanctions on Agrosoyuz Commercial Bank, the Russian financial institution, for "knowingly conducting or facilitating a significant transaction" on behalf of Han Jang Su, the Moscow-based chief representative of Foreign Trade Bank (FTB), North Korea's primary foreign exchange bank.

It also designated Ri Jong Won, the FTB's deputy representative based in Moscow, as well as FTB "front companies" Dandong Zhongsheng Industry & Trade Co., Ltd. (Zhongsheng) and Korea Ungum Corporation (Ungum).

The United Nations and the US had already previously designated Han and the FTB, and OFAC called for the expulsion of both Han and Ri.

OFAC noted that Agrosoyuz was still providing services to Han this year, in violation of Russia's UN obligations, and knowingly opened multiple bank accounts for at least three FTB front companies.

Agrosoyuz has processed millions of dollars in transactions via North Korean-linked accounts since at least 2009, according to OFAC.