"In Darfur, where we are acting ... with the full authority of the United Nations and the Security Council, we have a $30 million programme but have received only $2 million," said Chamberlin, a U.S. citizen.

The U.N. estimates that at least 180,000 people have died of hunger and disease in Darfur, and an unknown number have been killed in violence which intensified after rebels took up arms some two years ago and the government armed militia groups.

The agency also needs more money in Chad, where it runs camps for some 250,000 refugees who have fled the fighting in Darfur. Of $81 million required for Chad, only $30 million has been received, she added.

In southern Sudan, where the U.N. is sponsoring a recovery programme after two decades of civil war in which two million died and four million fled their homes, UNHCR appeals for its $61 million programme have so far brought in only $9 million.