There are signs that the acute food crisis affecting nearly a million people in southern Sudan is deteriorating despite the mounting of a massive international aid effort.

The UN's Operation Lifeline Sudan says that as it gets further access to areas it uncovers more need and the medical charity, Medecins Sans Frontieres, says in some cases half the severely malnourished children in its feeding centres are deteriorating because not enough food is getting through.

Every morning the nurse in charge at the MSF centre counts the bodies. Simone von den Berg says sometimes she sees as many as five but she hears about more.

Half of the children, she says, are not thriving. The problem is that the entire family shares a week's ration intended only for the children.

Apart from meagre wild fruits and leaves, there is no other food available. The feeding centres act as magnets for a desperate population which is prepared to travel far to camp outside as they are the only source of regular food.

Conscious of the growing emergency around the centre in Ajiep, the UN arranged the first food distribution for the area in a month. Enough maize was airdropped to give a month's half ration to 24,000 people.

But the estimated population in need is now put at 70,000. As the crisis grows throughout rebel-held southern Sudan, the UN has mustered the capacity to lift three times more food than in any previous Sudanese emergency.