In the dry wasteland of Sudan's war-racked Darfur region, the imprint of an ancient 8,000sq-mile underground lake has been discovered by geologists from Boston University. If confirmed, a lake as big as the area of Wales could replenish the region for a century. It is also raising hopes that one cause of the devastating civil war could be alleviated if drinking water is pumped to the surface.

The Egyptian geologist Farouk El-Baz, who led the research, hopes up to 1,000 deep wells would bring some relief to an area where conflict between nomadic herders and farmers has been exacerbated by climate change and dwindling water supplies.

Using satellite and radar images, Mr Baz and a team of 20 researchers found what appear to be streams emerging from a 5,000-year-old lake deep under the sands of northern Darfur, once replenished by surging rivers fed by rain.

Mr Baz says he showed the Sudanese government images of what appears to be an underground lake, and plans to return for an aerial survey by helicopter. He made a similar discovery in Egypt in the 1980s, which resulted in the drilling of 500 wells in arid regions. Mr Baz says he has a promise of equipment and manpower to drill the first 20 wells in Sudan.

A report by the United Nation Environment Programme says: "The scale of historical climate change, as recorded in northern Darfur, is almost unprecedented: the reduction in rainfall has turned millions of hectares of marginal semi-desert grazing land into desert. The impact of climate change is considered to be directly related to the conflict; desertification has added significantly to the stress on the livelihoods of pastoralist societies, forcing them to move south to find pasture."

Ban Ki-moon, the UN secretary general, said: "It is no accident that the violence in Darfur erupted during the drought." He added that camel herders used to replenish at the farmers' wells, and grazed stock on their lands until the rains stopped. Then, farmers fenced their land for fear it would be ruined by passing herds, leading to conflict.

One of the first to draw attention to global warming's capacity to generate conflict was the economist Jeffrey Sachs an adviser to the UN secretary general. He wrote: "Shifts in rainfall can bring down governments and even set off wars. The African Sahel, just south of the Sahara, provides a dramatic and poignant demonstration.

"The deadly carnage in Darfur, Sudan, for example, which is almost always discussed in political and military terms, has roots in an ecological crisis directly arising from climate shocks."

A report on how climate change posed a threat to global security said: "Darfur provides a case study of how existing marginal situations can be exacerbated beyond the tipping point by climate-related factors. It also shows how lack of essential resources threatens individuals and their communities, the region and the international community."

The drought and famine in the region in 1984-85 led to localised conflicts, pitting pastoralists against farmers in a fight for diminishing resources, culminating in war in 1989. But experts on Darfur say focusing on climate change alone may obscure other reasons and hamper the search for solutions.

Julie Flint, co-author of Darfur: The Short History of a Long War, says attempts to paint the conflict as simply resource-based "whitewashes the Sudan government". The "full-fledged tragedy", starting in 2003, was caused by the government's response to the rebellion, not by resource conflict, she said.

Geoffrey Dabelko, director of the Woodrow Wilson Centre, said: "The challenge is to avoid over-simplistic or deterministic formulations that equate climate change inexorably with genocide or terrorism."

* The EU is set to take a first tentative step towards sending forces to Chad to help the UN protect Darfuri refugees. An EU official said ministers would ask the EU's crisis management and military staff to plan a possible security mission.