Four aid agencies working in southern Sudan have called on the United Nations to take a greater role in ending the civil war and humanitarian crisis there, which they say has reached unimaginable proportions.

The aid agencies say at least one-and-a-half million people are thought to have died in the first ten years of the Sudanese civil war, and two-and-a-half million are at risk from the latest famine.

The BBC East Africa correspondent says the agencies fear renewed fighting in famine affected areas at the end of the rainy season and are frustrated that not enough is being done to bring about peace.

The agencies are Care, Save the Children Fund UK, Medecins sans Frontieres and Oxfam