There is little hope of peace in war-ravaged Sudan unless it addresses widespread environmental damage and climate change, a UN study has found.
Sudan has the world's largest refugee population, the UN says
The conflict in Darfur is spreading deserts and deforestation, threatening to raise ethnic tensions, it found.
But it says drought helped spark the Darfur conflict, as African farmers and Arab nomads fought over water and land.
At least 200,000 people have died and more than 2.4m have fled amid rape and looting in the four-year Darfur crisis.
Last week, UN Secretary-General Ban Ki-moon said climate change was partly to blame for the conflict in Darfur in an editorial for US newspaper The Washington Post.
'Fight for resources'
The UN Environment Programme (UNEP) report says competition over oil, gas, water, timber and land use are behind the "instigation and perpetuation" of decades of fighting throughout Sudan.
It says environmental degradation is one of the root causes of the conflicts - alongside economic, political and social issues - as these natural resources are depleted.
With more than five million internally displaced and international refugees, Sudan has the largest refugee population in the world today, the UN says.
It points to the spread of deserts by an average of 100km in the last 40 years, a loss of almost 12% of forest cover in 15 years and overgrazing of fragile soil.
"Ignoring these environmental issues will ensure that some political and social problems remain unsolvable and even likely to worsen, as environmental degradation mounts at the same time as population increases," the report said.
Refugee camps set up to provide shelter and care for the 2.4 million people who fled their homes amid the ongoing violence are causing further damage, the report says.
Boreholes dug to provide much-needed water supplies are depleting underground water reserves, and forests are disappearing as trees are chopped for firewood used by the refugees.
And as families attempt to rebuild their lives when the conflicts end, there will be a further drain on scarce resources such as land and wood.
The report also warns that the tragedy in Darfur could be repeated throughout North Africa and the Middle East as growing populations fight for limited water supplies.
The UN recommends Sudan work to reduce the environmental impact of its oil industry and agricultural practices, and prevent local conflicts over natural resources. It says rising oil revenues mean the country should be able to invest in these practices.
It also says all UN aid projects in the country should improve environmental practices in their operations.
The violence in Darfur started in early 2003 when ethnic African rebels took up arms against Sudan's Arab-dominated government.
The rebels said the government was oppressing black Africans in favour of Arabs amid tensions over water, land and grazing rights between the groups.