As the Ebola crisis worsens, the UN says 20 times more money is needed to fight the deadly virus.

Its described the epidemic as the biggest global health threat since Aids.

The Guardian has reported that the International Monetary Fund has changed its rules to allow West African countries to borrow more and run up bigger deficits in an effort to contain the disease.

International Monetary Fund managing director Christine Lagarde said it was dropping its normal opposition to extra borrowing for the three worst-hit countries, Sierra Leone, Guinea and Liberia.

Meanwhile UN secretary general Ban Ki-moon, said the response to the outbreak which has left almost 4,000 dead had so far been inadequate.

For those who have yet to pledge, I say please do so soon, he said. This is an unforgiving disease.

The Guardian says the appeal came as the presidents of the three countries said they could not cope with the crisis and pleaded with the international community to send more help.