Most African countries will fail to attain the United Nation's Millennium Goals on access to water and sanitation, the world body's environment agency said on Friday.

"Only eight countries in Africa are expected to attain the MDG target of reducing by half the proportion of the population without sustainable access to basic sanitation by 2015," the United Nations Environment Programme (UNEP) said.

The eight countries on course to fulfill that provision of the UN Millennium Development Goals (MDGs) are Algeria, Morocco, Tunisia, Libya, Egypt, South Africa, Angola and Botswana.

The finding is part of research carried out for the Africa Water Atlas which UNEP said uses hundreds of "before and after" shots and satellite images to reveal the continent's water crisis with unprecedented clarity.

UNEP also said that only 26 out of 53 African countries were on track to reach the MDG target of halving the proportion of the population without sustainable access to drinking water by 2015.

UNEP Executive Director Achim Steiner said the water atlas provided a volume of information that could be used to tackle Africa's water issues more effectively.

"From the dams triggering erosion on the Nile Delta to pollution in the Niger River Basin, the way infrastructure development or uncontrolled oil spills are impacting the lives and livelihoods of people are all brought into sharp relief," he said.

"The challenges of water scarcity in Africa are compounded by high population growth, socioeconomic and climate change impacts and, in some cases, policy choices," the statement said.

Africa is one of the most vulnerable continents to climate change and with a fast-expanding population, the amount of water available per person is declining, UNEP said.

The Millennium Development Goals are eight targets adopted in 2000 to be attained by 2015 on poverty, education, gender equality, health issues and the environment.