Four Chinese nationals and a Chinese company have been indicted on charges of helping North Korean entities involved in the proliferation of weapons of mass destruction, the US Department of Justice said Tuesday.

A federal grand jury in Newark, New Jersey, charged Chinese businesswoman Ma Xiaohong, her company, Dandong Hongxiang Industrial Development Co. Ltd., and three of the company's top executives with violating sanctions and conspiring to defraud the US and launder money, the department said in a statement.

The announcement comes as the US has been negotiating the dismantlement of North Korea's nuclear weapons program, with working-level talks expected to resume in the coming weeks.

Washington has maintained that all sanctions on North Korea must be enforced until the complete denuclearization of the regime.

"Through the use of more than 20 front companies, the defendants are alleged to have sought to obscure illicit financial dealings on behalf of sanctioned North Korean entities that were involved in the proliferation of weapons of mass destruction," Assistant Attorney General for National Security John Demers said.

Citing the indictment, the department said the four Chinese nationals established front companies in offshore jurisdictions such as the British Virgin Islands and the Seychelles from Dec. 2009 to Sept. 2015, and opened Chinese bank accounts under the front companies' names at banks in China with "correspondent" accounts in the US.

The defendants then used these accounts to conduct US dollar financial transactions for sales to North Korea, the department said.

"Any Chinese company conspiring to do business with sanctioned WMD proliferators through the US banking system should think twice," Assistant Attorney General Brian Benczkowski of the department's criminal division said.

The indictment quoted by the department also stated that DHID's core business was trade with North Korea and that it allegedly openly worked with North Korea-based Korea Kwangson Banking Corporation before that company was sanctioned by the US in Aug. 2009 for providing US dollar financial services to two other North Korean entities.

Those entities -- Tanchon Commercial Bank and Korea Hyoksin Trading Corporation -- have been sanctioned by the US for their ties to the Korea Mining Development Trading Co., which the US has described as North Korea's premier arms dealer and main exporter of goods and equipment related to ballistic missiles and conventional weapons.

The defendants face a maximum sentence of 20 years in prison for the most serious charge.

The charges were announced in September 2016. At the time, the US Treasury Department imposed sanctions on DHID in the first such action by the US against a Chinese company. (Yonhap)