Lack of resources has been blamed for causing the conflict
A vast underground lake that scientists hoped could help to end violence in Sudan's Darfur region probably dried up thousands of years ago, an expert says.
Alain Gachet, who used satellite images and radar in his research, said the area received too little rain and had the wrong rock types for water storage.
But the French geologist said there was enough water elsewhere in Darfur to end the fighting and rebuild the economy.
Analysts say competition for resources such as water is behind the unrest.
More than 200,000 Darfuris have died and two million fled their homes since 2003.
On Wednesday, Boston University's Farouk El-Baz said he had received the backing of Sudan's government to begin drilling for water in the newly-discovered lake, in North Darfur.
He said radar studies had revealed a depression the size of Lake Erie in North America - the 10th largest lake in the world.
But Mr Gachet, who has worked on mineral and water exploration in Africa for 20 years, said the depression identified by the Boston researchers was probably full of water 5,000 to 25,000 years ago.
"This lake was at the bottom of a broad watershed feeding the Nile above Khartoum," he said.
"This watershed is completely dry today on the southern border of Egypt, Libya and north-western border of Sudan - one of the worst areas in the world."
He accepted that the Boston researchers had a slim chance of being right, but he said he was not optimistic.
Further south, in the rebel-controlled Jebel Mara area of Darfur, Mr Gachet said he was helping a UN-backed project to drill for water.
"There is enough water within these aquifers to bring peace in Darfur... and even more - enough to reconstruct the economy of Darfur."
Earlier in the week Hafiz Muhamad, from the lobby group Justice Africa, told the BBC the "root cause" of the conflict was lack of resources.
He said "drought and desertification" in North Darfur had led the Arab nomads to move south, where they came into conflict with black African farmers.
Last month, the UN Environmental Programme (Unep) said there was little prospect of peace in Darfur unless the issues of environmental destruction were addressed.