ATHENS African nations led by Somalia, Mauritania and Sudan have the most precarious water supplies in the world while Iceland has the best, according to a survey on Thursday that aims to alert companies to investment risks.
The ranking, compiled by British-based risk consultancy Maplecroft, said climate change and a rising world population meant that stresses on supplies would be of increasing concern in coming decades for uses from farming to industry.
A "water security risk index" of 165 nations found African and Asian nations had the most vulnerable supplies, judged by factors including access to drinking water, per capita demand and dependence on rivers that first flow through other nations.
Somalia, where just 30 percent of the population has clean drinking water, topped the list above Mauritania, Sudan, Niger, Iraq, Uzbekistan, Pakistan, Egypt, Turkmenistan and Syria.
At the other end of the scale, rain-soaked Iceland had the most secure supplies, slightly better than Norway and New Zealand.
"With climate change there is going to be a greater strain on limited water resources in many nations," Anna Moss, author of the study, told Reuters.
Shifts in monsoon rains and melting of glaciers, for instance, could disrupt supplies with the potential to cause cross-border conflicts. Construction of hydropower dams or more irrigation, for instance, can disrupt supplies downriver.
The study said irrigation accounted for 70 percent of freshwater consumption across the globe. Industry uses another 22 percent.
It said that companies including Anglo American, Rio Tinto, Bristol-Myers Squibb, Marks & Spencer, Coca-Cola or Devon Energy were among those seeking to reduce water use.
Water stress was not only a problem in poor nations. Nations such as the United States and Australia have regions that are at risk.
"Countries in Europe, such as Bulgaria, Belgium and Spain, have issues with water stress," Moss said. Bulgaria ranked 47 on the list, Belgium 50, Spain 68, Australia 95 and the United States 104.
(Editing by Ralph Boulton)