Gold tarnished: Inside the illegal mine at Nyamurhale

As demand for gold booms around the world, the UN is calling for tougher measures to prevent smuggling and the exploitation of workers in unregulated mines.

Much of the gold bought and sold each year cannot be properly sourced, making it difficult for even the most scrupulous of traders to avoid using conflict metals.

Humphrey Hawksley reports from Nyamurhale in the Democratic Republic of Congo.