In February, the United Nations published a lengthy report (pdf, p52) with information about 20 North Korea-flagged vessels that were owned or operated by foreign companies, in violation of UN sanctions.

This week, Hong Kong-based online publication HK01 published a series of investigative reports digging into the UN report. In one article (link in Chinese), it found that one of the North Korea-flagged vessels had links that can be traced back to China’s biggest state-owned investment company—until the ship was sold to a North Korean firm just two months ago.

The cargo vessel Hae Bang San—which can carry up to 1,820 metric tons (2,006 tons) of goods—routinely sailed between North Korea and China’s northeastern port cities in July and August, HK01 noted, citing data from industrial site MarineTraffic. According to the UN’s February report, Hae Bang San was owned by a Hong Kong-based front company called Hongkong Complant Intl Trans (pdf, p. 205). Citing company registry information, HK01 found that Hongkong Complant—which bought the North Korean vessel in 2010—lists two Chinese citizens as its shareholders, Zhang Xiaofen (张晓汾) and Wang Junliang (王君良). Zhang and Wang’s emails as listed in the registration documents reportedly belong to Chinese state-owned company COMPLANT International Transportation Co., Ltd (COMTRANS).

Zhang is the vice chairman of the board of COMTRANS, while Wang is a board member, according to Chinese company registration information (link in Chinese). Both also serve as senior executives at several COMTRANS subsidiaries.

Founded in 1993 by China’s commerce ministry, Beijing-headquartered COMTRANS used to be a government organ handling China-assisted construction projects in developing countries since the 1960s. Since then, it’s been turned into a logistics company owned by State Development & Investment Corporation (SDIC), China’s biggest state-owned investment holding group.

Hae Bang San appeared on MarineTraffic’s online tracking system for the last time on Aug. 17 in waters near the Chinese coastal city of Dalian. In the same month, Hongkong Complant sold the vessel to an untraceable North Korean company, HK01 reported, citing data from research firm IHS Markit.

COMTRANS and SDIC didn’t reply to Quartz’s requests for comment. Hugh Griffiths, one of the UN experts who authored the February report, told HK01 that the UN is looking into the case, and refused to comment before any new information emerges.