South America sees new gold rush

From the vantage point of a trench, four soldiers watch as a Colombian military helicopter returns from an operation in the north-west of the country, an area known as the "red zone" where the illegal drugs trade is big business.

But the crew returning to the airport of Caucasia had not been on a raid to arrest drug dealers nor to destroy a coca plantation.

Their target was illegal gold mines. Since the start of the global economic crisis in 2008, gold has risen in price by 100%, and in South America production of this precious metal is booming.

The impact of the price rise has been felt across nine countries in the region with workers migrating to mining areas and politicians striving to attract foreign investment for the mining industry.

Governments have also been forced to step up efforts to tackle illegal mining, amid fears that it is damaging the environment and creating lawless encampments where taxes are evaded and women sexually exploited.

"All the areas explored 15, 20 years ago are being explored again"The authorities in Colombia say an even more worrying development is that illegal gold mines are being used to support guerrillas from the Revolutionary Armed Forces of Colombia (Farc).