Worldwide demand for water is rising just as access to safe drinking water and sanitation remains inadequate in much of the developing world, the United Nations said Monday, calling for better management to alleviate water shortages.

Population growth and mobility, as well as increased energy production, especially of biofuels such as ethanol, are contributing to the high demand for water, UNESCO said on the first day of a global water forum in Istanbul, Turkey's largest city.

"With increasing shortages, good governance is more than ever essential for water management. Combating poverty also depends on our ability to invest in this resource," said Koichiro Matsuura, director-general of the U.N. agency.

Thousands of activists, entrepreneurs, mayors, parliamentarians and business executives have gathered for the weeklong World Water Forum, which is held every three years to promote ideas about conserving, managing and supplying water. Climate change and the impact of the global economic meltdown are key issues on the agenda this year.

Earlier Monday, police used truncheons and tear gas to disperse a small group of Turkish demonstrators who rallied outside the conference center to protest what they said was the forum's promotion of water as a commodity. The protesters said big water companies benefit from privatization, and that the poor are entitled to clean water as a "human right."

About 20 protesters who tried to enter the complex in Istanbul were detained, according to an Associated Press photographer at the scene.

The forum, whose members include the World Bank and the International Committee of the Red Cross, deny they represent special interests. Still, companies were exhibiting water-related products at the conference complex on the Golden Horn, the city's peninsula.

UNESCO said half a billion people in Africa lack access to adequate sanitation, and that 5,000 children die daily from diarrhea, a disease that can be prevented with clean water. The agency said the number of people living on less than $1.25 a day is roughly the same as the number without access to safe drinking water.

"In America, diarrhea is bad takeout," said John Sauer of Water Advocates, a U.S.-based nonprofit group. "In Chad, it's the difference between life and death."

Water demand is increasing partly because of the rising production of ethanol and other biofuels in countries such as Brazil and the United States. Large amounts of water and fertilizers are needed to grow the crops needed to make biofuels, placing additional stress on the environment, according to UNESCO.

The agency said many countries have legislation that protects and manages water resources, but that the reforms "have yet to have any noticeable effect" because water policy needs to include decision-makers in other fields such as agriculture, energy, trade and finance.