The charity Médecins Sans Frontières is making a plea this weekend for additional help for the four million people living in the area surrounding the Aral Sea who have poor access to potable water. The Aral Sea lies within Uzbekistan and Kazakhstan.

The local drinking water has a high salt content and is often contaminated by pesticide residues, phenols, and, occasionally, heavy metals. At the second world water forum being held in the Hague this weekend, water specialists, politicians, and officials from across the globe are meeting to discuss plans to try to ensure that everyone has access to clean water by 2025.

Médecins Sans Frontières is asking for particular help for those affected by the economic and environmental consequences of the drying up of the Aral Sea. The shrinking of the Aral Sea, once the world's fourth largest inland body of water, to half its size and one third of its volume began in the early 1960s, when, in the pursuit of intensive cotton production, irrigation diverted water from the two rivers that feed the sea.

Despite 10 years of international assistance and millions of dollars spent on assessments, access to safe drinking water remains insufficient. Médecins Sans Frontières has been working in the area since 1998, providing medical assistance to the population and conducting research into the environmental factors affecting health. Access to a system that supplies safe water is one of the most pressing issues.

"In Kara-Kalpak, [an autonomous republic within Uzbekistan that borders the Aral Sea] only 84%of the urban population and 32%of the rural population have access to potable water," said Joost van der Meer, the charity's research director in Tashkent, who is attending the conference. "Over a quarter of the population uses irrigation canals as their main water source," he added. "Faecal contamination and diarrhoeal diseases occur frequently compared with regional standards.

The proportion of infant deaths due to diarrhoea is as high as 29.1% compared to around 16%for the rest of the region. Outbreaks of other waterborne diseases such as hepatitis A are also common," Dr van der Meer explained. Ian Small, head of the charity's mission in Uzbekistan, said: "Far more non-governmental organisation involvement is needed for a catastrophe of this scale."