The Democratic Republic of Congo has banned exports of copper and cobalt concentrates, according to a government order reviewed by Reuters on Thursday.

The order, dated June 29, was signed by Mines Minister Louis Kabamba Watum, Foreign Trade Minister Julien Paluku Kahongya and Economy Minister Daniel Mukoko Samba.

It states plainly: "the export of copper and cobalt concentrates is prohibited."

The move marks a major escalation in Congo's campaign to force mineral processing to happen domestically rather than abroad, keeping more value from its mineral wealth inside the country. Congo is the world's largest cobalt producer and the second-largest supplier of copper.

The ban took effect immediately. Alongside it, Congo introduced a new tax regime targeting economically significant mining by-products, part of a broader push to raise revenue from its mining sector. That tax regime carries a three-month transition period before taking full effect.

There's a safety valve built into the policy. The mines minister has authority to grant one-year export waivers under what the order calls "strategic" circumstances.

The ban affects some of the biggest names in global mining. Major operators active in Congo include China's CMOC — the world's largest cobalt producer — along with Glencore, Huayou Cobalt, Zijin Mining, Ivanhoe Mines and Eurasian Resources Group.

Details on how the waiver process will work, and which companies may seek exemptions, remain unclear.