JOHANNESBURG, International relief agencies say the situation in Somalia and Yemen has become so dire that millions of people are under threat of starvation and the International Committee of the Red Cross says the world has just three months to avert such a situation.

As drought and war wreak havoc on crops and block the flow of aid across the region, the Red Cross says it needs 300 million US dollars to fund its work in Somalia, Yemen, South Sudan and northeastern Nigeria. The ICRC has appealed for 400 million USD for its operations in the four countries this year, but has received only 100 million USD so far.

"This is not business as usual. Twenty million people facing starvation is not something that we are dealing with everyday and therefore, we really need to act now. If we act now, especially in Yemen and in Somalia, famine can be averted," says Dominik Stillhart, the Director of Operations at the ICRC.

"We need to learn the lessons from 2011 where the response was too slow, too little and 260,000 people died of starvation -- more than half of them children under the age of five -- so we really need to act now".

In Somalia, some 320,000 children under the age of five are acutely malnourished, and 50,000 of them are so severely malnourished that they risk dying without emergency intervention.

Meanwhile, the United Nations Children's Fund (Unicef) says South Sudan's five million people don't have access to safe water in a country where an on-going drought has further complicated the situation.

"Why is safe water so important for nutrition? Because if you don't have safe water, you are liable to catch either a waterborne disease or get diarrhoea. A simple bout of diarrhoea can induce malnutrition really in a matter of days. And if that malnutrition is severe, the child will die," says Unicef's South Sudan acting country representative, Jeremy Hopkins.

While the UN calls for co-ordinated global efforts to help Somalia, South Sudan, Nigeria and Yemen, the relief agencies say humanitarian aid is slow to reach some of those on brink of catastrophe.