Competition for scarce water resources could trigger the next World War, Pope Francis warned on Friday.
"I wonder... whether we are not heading for a Great World War over water," Francis said.
He was addressing a two-day seminar at the Vatican on public policies for water and sanitation management.
"Safe drinking water is a universal right," Francis said adding that it pained him to see countries passing legislation to deny people this right.
One thousand children die each day from water-borne diseases, while millions drink unclean water, he said calling the figures "very serious".
States and organisations "must find effective solutions capable over overcoming the selfishness that is denying all human beings this crucial right," the pontiff said.
"This is also a duty," Francis added.