Aid agencies working in the world's largest refugee camp in Kenya say they are running out of funds, putting tens of thousands of lives at risk.Eight organisations, including Oxfam and Save the Children, say they are facing a shortfall of $25m (£16m), but that the need is greater than ever.The population in Dadaab, which lies near the Somali border, has increased by a third over the past year.It is now home to almost half a million people, mostly from Somalia.Last year, tens of thousands of people flooded into the camp to flee poverty and violence in Somalia, made worse by the region's most severe drought in 60 years, with famine declared in some areas.The UK appeal raised £79m ($122m) - more than for any other food crisis.BBC world affairs correspondent Mike Wooldridge says that, according to the aid agencies, many refugees are still in tents that are quickly destroyed in the harsh climate.