The charcoal cutters of Virunga National Park know that their trade is illegal. Their fires, where they turn freshly cut olea trees into blackened cooking fuel, are built far from prying eyes in the war zone.

The illegal trade in charcoal has cut a strip of savannah through the Democratic Republic of Congo's tropical rainforest, threatening the survival of the park's rare mountain gorillas.

Now the industry, worth $35 million a year, is having an equally devastating effect on human populations as the battle for control of the region's rich natural resources fans the flames of civil war.

The forest close to Rubare is home to Rwandan Hutu militias, who fled their homeland after Tutsi rebels took power in 1994. Today they are known as the Democratic Forces for the Liberation of Rwanda.

Back then they were the death squads of the Interahamwe — meaning "those who work together" — responsible for killing hundreds of thousands of Tutsis and moderate Hutus.

One of the cutters, Mumbere Ambrose, used a machete to hack some branches into a convenient size for charcoal as a chainsaw buzzed close by.

To get access to the best trees, Ambrose is forced to give money to the Hutu militias, who hold much of the southern reaches of Virunga, skimming cash from the charcoal producers to fund their war.

Elsewhere, countless rebel factions are vying for control of other natural resources — among them gold.

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