Some of the world's most recognisable technology brands — including Amazon, Ericsson, Sony, Microsoft, Nvidia, Toyota and Vodafone — have likely been using coltan linked to the M23 militia, a rebel group accused of widespread atrocities in the Democratic Republic of the Congo, according to a year-long investigation by Global Witness. The group says the mineral was smuggled out of occupied mines and moved through Rwanda into global supply chains, bypassing existing safeguards designed to prevent conflict financing.

Coltan, a metallic ore essential for manufacturing the capacitors found in mobile phones, computers and electric vehicles, is mined in large quantities around Rubaya, a site in North Kivu province — a region in the mineral-rich east of the DRC — that holds roughly 15% of the world's known reserves. M23, a militia backed by up to 7,000 Rwandan troops deployed inside Congolese territory according to UN assessments, captured the Rubaya mines two years ago and now levies a tax on every kilogram extracted. UN experts estimate the group collects nearly £600,000 a month from coltan taxation alone — revenue that funds operations in which thousands of civilians have been killed, hundreds of thousands displaced, and widespread sexual violence and torture documented. Rwanda denies supporting M23.

Global Witness says five of Rwanda's seven largest coltan exporters are purchasing conflict minerals smuggled from DRC, with large volumes now entering Rwanda through Goma, the eastern DRC border city that M23 seized in January 2025. From Rwanda, the coltan is sold through middlemen to smelters in China and Kazakhstan, where it is processed into tantalum before entering mainstream electronics manufacturing. A separate Human Rights Watch report, published in June, documents systematic forced recruitment, beatings, dehydration and summary executions at M23-run military camps in North Kivu following the fall of Goma, with witnesses reporting mass graves and satellite imagery showing ground disturbances at one site. HRW also criticised the Congolese government for supporting armed groups, including factions accused of violence against displaced civilians near Goma.

The Global Witness investigation found that traceability systems relied upon by international companies — notably the International Tin Supply Chain Initiative (ITSCI) and the Responsible Minerals Initiative (RMI) — have largely failed to detect conflict coltan entering supply chains. Companies named in the report said they do not directly purchase raw minerals and rely on certified industry programmes for due diligence. Ericsson said it was treating the allegations with seriousness and had identified two named smelters appearing in its supply-chain data; Amazon said it was requesting additional due diligence from relevant suppliers. Global Witness is calling on companies to suspend coltan purchases from Rwanda until M23 withdraws from Rubaya, unless they can verify the mineral's origin through direct checks.

The findings highlight a persistent gap between corporate responsibility commitments and on-the-ground reality in conflict zones. "Behind our everyday tech lies a supply chain tainted by violence, exploitation and human suffering," said Alex Kopp, senior policy and advocacy adviser at Global Witness, who urged governments to impose sanctions on those enabling M23's occupation. Eastern DRC has experienced cycles of armed conflict for three decades, and the region's vast mineral wealth has long been identified as both a driver of and a source of financing for that violence.