The US imposed sanctions Wednesday on three foreign companies it accuses of helping North Korea with the illicit shipments of goods to fund its nuclear program.

The Treasury Department said it was taking action against the companies, which are based in China, Russia and Singapore, as well as the head of the Russian firm.

The move blocks any assets that they may have in US jurisdictions and bans Americans from doing business with them.

It comes as the US continues to press for full compliance with international sanctions against North Korea while it continues talks with the North on ending its nuclear program.

"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," Steven Mnuchin, the US Treasury Secretary, said in a statement.

"Treasury will continue to implement existing sanctions on North Korea, and will take action to block and designate companies, ports and vessels that facilitate illicit shipments and provide revenue streams to the DPRK.

"The consequences for violating these sanctions will remain in place until we have achieved the final, fully verified denuclearisation of North Korea."

Those targeted on Wednesday are the China-based Dalian Sun Moon Star International Logistics Trading Co. and its Singapore-based affiliate, SINSMS Ltd., along with Russia's Profinet Ltd. and its director general.