The US Treasury Department designated two entities and two individuals in the Democratic People's Republic of Korea subject to sanctions in line with United Nations resolutions over the country's nuclear and ballistic-missile programs.

A senior Treasury official said after announcing the designations on Thursday that the US government remains in close contact with China over UN-backed efforts toward "complete denuclearization of the Korean Peninsula".

Daedong Credit Bank and a front company identified by US officials as DCB Finance Ltd can have their assets frozen, under a White House executive order in 2005 from then-president George W. Bush against alleged proliferators of weapons of mass destruction and their supporters.

The two individuals targeted on Thursday are Kim Chol-sam, 42, a DCB Finance representative, and 62-year-old Son Mun-san, head of external affairs for the DPRK's General Bureau of Atomic Energy, which runs the nation's nuclear development efforts.

The bank, the front company and the two men are also barred from doing business with any US companies.

Kim is suspected of facilitating transactions worth hundreds of thousands of dollars "and likely managed millions of dollars in North-Korean related accounts", the department said. Since at least 2006, Daedong Credit Bank has used DCB Finance, which is registered in the British Virgin Islands, to carry out international financial transactions as a way to avoid scrutiny by financial institutions that won't do business with Pyongyang.

David Cohen, Treasury undersecretary for terrorism and financial intelligence, was asked during a conference call with reporters about the assertion that in representing DCB Finance, Kim worked out of the company's office in the northeastern Chinese city of Dalian, Liaoning province.

"I can't speak to what the Chinese may know about the activities of Daedong Credit Bank or Kim Chol-sam operating out of Dalian," Cohen said. "I think we have over the years, and particularly over the last several months, been communicating on a very regular basis with the Chinese on a whole range of issues related to the North Korean nuclear and ballistic-missile program and have had a number of, I think, very productive conversations with them on these topics.

"We are, as I said, hopeful that countries around the world will take notice of what we're doing today - that obviously includes the Chinese - and we will continue to talk to the Chinese about Daedong and about the whole range of threatening behavior that we've been seeing from the North Koreans," he said.

Thursday's action was based on allegations that Daedong, DCB Finance and Kim provided financial services to Tanchon Commercial Bank, or TCB, and two representatives of Korea Mining Development Corp, known as KOMID. In 2005, the Treasury Department designated both entities as targets for asset freezes, describing KOMID as the "premier arms dealer" for the DPRK government. In March of this year, Treasury officials added representatives of TCB and KOMID to the financial-target list.

The designation of Son was due to his role in directing research for the DPRK atomic energy bureau, including the Yongbyon Nuclear Research Center, home to a 5-megawatt plutonium-production research reactor as well as fuel fabrication and reprocessing facilities. The bureau was designated by the United Nations in July 2009 and two months later by the US.

Cohen called Thursday's action "another step to disrupt North Korea's nuclear program, to ramp up the pressure on the North Korean regime, and to fulfill our obligations under UN Security Council resolutions".

The council adopted its most recent resolution, No 2094, against DPRK nuclear and ballistic-missile programs on March 7. The resolution, whose passage came three weeks after Pyongyang launched its third nuclear test, drew strong support from China.

Cohen praised China's support in the UN, along with the decision in May by Bank of China Ltd, which has US operations, to stop doing business with the Foreign Trade Bank of North Korea. Washington accuses the bank - the DPRK's main financial institution for foreign-exchange transactions - of financing the nuclear and missile programs. In March, the Treasury Department announced sanctions to cut off the bank and several DPRK officials from the US financial system.

"We've been in very close consultation with the Chinese over the last several months, and going back before that, on issues having to with North Korean financial activity. I think we have seen over the last several months the Chinese, and Chinese banks in particular, taking steps to limit their exposure to North Korean financial institutions including the Foreign Trade Bank and we will see what transpires with respect to Daedong Credit Bank after today's action," Cohen said.