(bbc) Western mineral firms are fuelling violence in the Democratic Republic of Congo by failing to check where their raw materials come from, activists say. Global Witness says companies sourcing minerals used in electronic gadgets are buying them from traders who finance rebel and government troops. It calls for the UK-based Amalgamated Metal Corporation (AMC) and others to have assets frozen over the issue. AMC, whose subsidiary Thaisarco sources tin from DR Congo, denies the claims. The Global Witness report focuses on the troubled region of eastern DR Congo, where various rebel groups and government troops control large parts of the trade in minerals including coltan, cassiterite and gold. They use the industry to fund conflicts which have seen some 100,000 people displaced from their homes in recent months, in addition to mass killings and rapes, mostly in North and South Kivu provinces.