European governments must wield their influence and engineering skills more effectively to prevent conflicts over water supply that could threaten global security, the European Union's policy chief Catherine Ashton said.
The EU has a strategic interest in ensuring stability in regions with some of the world's biggest water problems, including North Africa after the Arab Spring revolts and Central Asia, which holds crucial energy reserves.
Ashton said the Nile basin was a particular concern.
"If managed well, the Nile holds the potential to catalyze regional integration and to help bring prosperity and stability to a vast area," she said in written responses received late on Friday to Reuters' questions.
"If handled poorly, each of the Nile countries could feel the negative consequences in their economic and social development."
Along the Nile, growing demand for water due to population growth, foreign investment and climate change pits Egypt's new government against upstream states such as South Sudan, Ethiopia and Rwanda, who are frustrated by what they see as Cairo's disproportionately large share of the river's water.
In Central Asia, one of the world's driest places, poor Soviet-era planning has left countries heavily dependent on thirsty crops such as cotton and grain, leading to tensions over water use and dam construction.
Uzbek President Islam Karimov said on Friday a dispute over water resources risks provoking military conflict in the former Soviet region.
Ashton, who was hosting a meeting of EU foreign ministers in Cyprus where water security was discussed, said the bloc would offer its know-how in order to help calm tensions in the region.
"Central Asia's increasing demand on a limited, shared resource carries risks but also opportunities for cooperation in the entire region and we will continue our efforts to help the region in this direction," she said.
With the world population predicted to grow to more than 9 billion in 2050, from 7 billion, demand for food is expected to increase by 70 percent in the next four decades, United Nations forecasts show, putting unprecedented strain on water resources.
"Water shortages, poor water quality, droughts and floods are likely to affect many places over the next few years and this can lead to instability and insecurity, which could have a direct bearing on Europe," Ashton said.
Experts say the European Union could help water-starved countries in North Africa better manage their water usage, helping to address criticism that Europe has not reacted effectively to challenges stemming from the Arab Spring.
"Where the EU may have a role to play is in the area of water sustainability [and] reuse of water waste," said William Lawrence, North Africa Project Director at the International Crisis Group.
"If downstream countries are using less water and using it better, then this can address upstream politics, which can be cantankerous."