(CNN) A quarter of the world's population is living in regions of extremely high water stress -- with "once unthinkable" water crises becoming common, researchers have said.

With the climate crisis biting, 17 countries -- home to one in four people on the planet -- are deemed to be "extremely high water-stressed," meaning they are now consuming more than 80% of their available water every year, the World Resources Institute (WRI) has revealed in a report.

And the growing shortages are fueling the risk of conflict in such countries, concentrated in the Middle East and North Africa, the researchers say.

Paul Reig, director of WRI's Aquedact water risk project, told CNN that the high level of demand relative to supply in these areas "puts huge pressure on available water resources and poses a threat to agricultural, industrial and domestic water users that rely on it."

Qatar is ranked as the world's most water-stressed country, followed by Israel and Lebanon, Iran and Jordan. In Africa, Libya and Eritrea are suffering the worst shortages.

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