Around 800 million people lack access to clean drinking water, UNICEF said in an annual report issued on Wednesday. The paper, focused on the "right to water," was released in Berlin and New York just hours before the start of the UN's Rio+20 summit in Rio de Janeiro.

"The poorest families profit too little from advances in the provision of basics like water, food, health care and education," UNICEF Germany director Christian Schneider told the Passauer Neue Presse daily.

Such social inequality is a threat to stability and a key problem when it comes to sustainable development, UNICEF said.

Effects of climate change

Every year, 375 million people are threatened by floods, famines or storms. The situation is especially dramatic in the Horn of Africa and Sub-Saharan Africa. There periods of drought and famine were occurring within ever smaller time spans.

UNICEF Germany plans to provide 500,000 children in countries such as Somalia and Cambodia with access to clean water and sanitary facilities over the next three years to tackle the problem.

Schneider underlined the importance of the sustainability conference in Brazil.

"In Rio, it's not about an environmental dictatorship, as some critics say, but rather it's about a new balance of business, economic, and social reason."

ncy/ccp (dpa, AFP, epd)