The police in northeastern China have announced a criminal investigation into a Chinese conglomerate that does extensive trade with North Korea, which researchers in South Korea and the United States say included materials that can be used in the production of nuclear weapons.

The Public Security Department of Liaoning Province said on a government website last week that the Hongxiang conglomerate, based in Dandong, a major trading center with North Korea, was suspected of “serious economic crimes.”

“During their work, the Liaoning public security authorities discovered that for a long time the Dandong Hongxiang Industrial Development Company Ltd. and a relevant responsible individual engaged in suspected grave economic crimes during trading activities,” the department said.

The police did not specify whether the company’s prominent chairwoman, Ma Xiaohong, was under investigation, nor did it say whether the company was the object of scrutiny for its North Korean business, which makes up the bulk of its trade.