STOCKHOLM, Aug. 18 (Xinhua) -- Some 2500 scientists, politicians and officials from 140 countries gathered here Monday to begin a week-long conference to seek ways to address global water challenges.

　　The international conference will address a wide variety of critical water-related issues with a special focus on sanitation and climate, said Anders Berntell, executive director of the Stockholm International Water Institute.

　　"Billions of people in the world live without sustainable access to safe drinking water or suffer ill health due to poor sanitation," said Berntell at the inauguration of the World Water Week, which runs through Saturday.

　　The reason for the growing water challenges is not climate change, but the world's ever-increasing population, Berntell added.

　　Gunilla Carlsson, Sweden's minister for international development cooperation, said the world must strike a balance between water resources and development, especially in developing and poor nations.

　　About 20 percent of the world's population in 30 countries face water shortages, and 88 percent of all diseases in the world are caused by unsafe drinking water, inadequate sanitation and poor hygiene, she added.

　　"It is indicated that 30 percent of the world's population in 50 countries will suffer from water shortages in 2025," Carlsson said.

　　The minister also urged all conference participants to work for better sanitation and strive to ensure global and individual water security.

　　The World Water Week in Stockholm is a leading annual global meeting place for capacity-building, partnership-building and follow-up on the implementation of international processes and programs in water and development.