The experts said in a report released Monday that "gold remains by far the mineral most used to finance armed elements and criminal networks" in the vast resource-rich DR Congo.
Most gold produced in the country is smuggled through neighboring countries to Dubai and the United Arab Emirates, said the report presented to the Security Council on December 28.
The experts' investigations found that several military officers were involved in gold production, which is in violation of army rules and the country's mining code.
The military opened investigations in September of three generals and two colonels for their alleged involvement in gold mining in South Kivu.
But in November, the UN group was told that there would be no prosecutions.
"Considering the amount of information publicly available... the group is concerned that a failure by the Congolese authorities to prosecute would maintain a cycle of impunity and undermine efforts to put an end to the involvement of some FARDC officers and criminal networks in the natural resources sector," said the report.
In particular, the experts cited diggers and gold traders as reporting that army colonel John Unega had "controlled a mining pit from April to July 2016, at the peak of gold production" in the Mangbwalu region of eastern DR Congo.
The experts also called on Kinshasa to investigate the activities of Kimia Mining in eastern DR Congo, which is allegedly owned by Chinese nationals.
An army unit has been deployed to protect the company's dredging operations on the Ituri river even though the governor of Ituri in July suspended all dredging over environmental concerns.
The group of experts said they had tried to contact the firm's owners, including through the Chinese government, but had yet to receive information.