Click here to watch Guardian film on violence in eastern Congo's mines

Conflict minerals are used by armed groups to fund violence and insurrection. Global Witness’s work on conflict minerals currently focuses on the Democratic Republic of Congo (DRC) where fighting has continued for over 10 years, driven by the trade in valuable minerals. Millions of people have died, and many more have been displaced.

There are four main minerals being mined in the Congo: cassiterite (the ore for tin), coltan (the ore for a rare metal called tantalum), wolframite (tungsten ore), and gold. The illicit trade provides rebel groups and units of the national army with tens of millions of dollars a year that they use to buy guns and shore up their rival campaigns.

The electronics industry is one of the main destinations for these metals, which end up in mobile phones, laptops, and other consumer products.  Tin is used as a solder in circuit boards; tantalum goes into capacitors, small components used to store electricity; tungsten is used in the vibrating function of mobile phones; gold is also used by the electronics industry – as a coating for wires.

World prices for each of these metals have been rising over the past year, giving armed groups in the eastern Congo all the more incentive to target or keep hold of the mines.

Global Witness is calling on the DRC government to demilitarise the mining sector immediately. We are also urging donor governments and electronics companies to do their bit to clean up this bloody trade by exercising proper controls over their supply chains.