The United States imposed sanctions on a Russian port service agency and Chinese firms for aiding North Korean ships and selling alcohol and tobacco to Pyongyang in breach of US sanctions.
The US Treasury said in a statement on Wednesday that China-based Dalian Sun Moon Star International Logistics Trading Co Ltd and its Singapore-based affiliate SINSMS Pte Ltd had netted more than $1 billion a year by exporting alcohol and cigarette products to North Korea.
The department also sanctioned Russian-based Profinet Pte Ltd and its director general, Vasili Aleksandrovich Kolchanov, for providing port services on at least six occasions to North Korean-flagged ships.
Kolchanov was personally involved in North Korea-related deals and interacted directly with North Korean representatives in Russia, the department said.
"The tactics that these entities based in China, Singapore, and Russia are using to attempt to evade sanctions are prohibited under US law, and all facets of the shipping industry have a responsibility to abide by them or expose themselves to serious risks," US Treasury Secretary Steven Mnuchin said in the statement.
The sanctions mandate that no US citizen can deal with any of those designated in the order, and any of their properties in the United States "must be blocked", the Treasury said.
The United States has been pressuring North Korea via sanctions to give up its nuclear weapons programme.
China's Foreign Ministry said in a statement that Beijing has always strictly enforced UNSC resolutions on North Korea and did not allow Chinese firms to engage in activities that violated them.