Mining firms in the Democratic Republic of the Congo (DRC) owe an estimated US$3.7 billion in unpaid customs duties and fines dating back to 2008.

This is according to an unpublished report commissioned by the public prosecutor’s office dated November 2013, which forms part of an ongoing investigation by the government into companies operating in its copper-rich Katanga province. Suspected malpractice by customs agents is also being investigated.

11 companies have been implicated, including Mutanda Mining, a copper miner 69 percent-owned by Glencore Xstrata, although some firms have queried the accuracy of the report’s findings. The public prosecutor has said that it is too early to draw conclusions about the outcome of the investigation.

Glencore has denied any misconduct, saying the report is inaccurate and that the company has not agreed to any penalties. “Contrary to what is stated in the draft document, no contact was made by the ‘mission’ with Mutanda mining. Mutanda has no outstanding taxes or fines,” Glencore said.

Energy and infrastructure challenges have placed the government under pressure to assist its population struggling with poverty, and recovering lost revenue from the sector has become a top priority. The DRC is world’s eighth-largest producer of copper, having produced 600 000 t in 2012.