UN aid agencies need $4.4 billion in emergency funding to address famine in Nigeria, Somalia, South Sudan and Yemen, UN Secretary General Antonio Guterres said Wednesday.

More than 20 million people face starvation in the four countries and action is needed now to avert a humanitarian disaster, Guterres told a news conference at UN headquarters.

"We need $4.4 billion by the end of March to avert a catastrophe," he said.

So far, the United Nations has raised $90 million to fund a global response to the four famine alerts, which are unprecedented in recent decades.

South Sudan on Monday declared a famine in parts of the north, while Fews Net, the famine early warning system, has said that some remote areas of northeast Nigeria are affected by starvation since late last year.

There has only been one famine since 2000, in Somalia. At least 260,000 people died in the 2011 disaster -- half of them children under the age of five, according to the UN World Food Program.

The UN children's agency UNICEF this week said almost 1.4 million children acutely malnourished in Nigeria, Somalia, South Sudan and Yemen could die as food shortages worsen in the coming months.

Of the four famine alerts, only one -- Somalia -- is caused by drought, while the other three stem from conflicts, described as "man-made food crises."

In Yemen, where war has been raging for nearly two years, about 7.3 million people need food aid now, in the "largest food insecurity emergency in the world," said Guterres.

- Un-blocking aid -

The Saudi-led coalition waging a military campaign against rebels in Yemen has been accused of imposing a blockade on Yemen, which relies almost entirely on imports.

The UN chief appealed to warring sides to allow aid workers to reach starving civilians.

"The situation is so dire. This is the moment in which international humanitarian law must be respected by all and access must be granted to all areas," said Guterres.

Across northeast Nigeria, some 5.1 million people face severe food shortages and nearly 500,000 children are suffering from acute malnutrition as the conflict with Boko Haram militants grinds on.

Famine has already been declared in two counties of South Sudan and nearly 5 million people are in desperate need of food.

Guterres, who took over from Ban Ki-moon on January 1, appeared at a news conference with top aid officials who stressed they had contingency plans in place, but needed funds to swing into action.

The appeal came as humanitarian aid groups are already struggling to meet needs in Syria and cope with the global refugee crisis.

The International Rescue Committee said Wednesday that the famine designation in South Sudan meant that people were already dying and that the international response was too late.

"These crises remain among the least discussed and most underfunded in the world despite their extraordinary scale, scope and man-made origins. This is absurd," said Ciaran Donnelly, international programs director at the IRC.

"The IRC and other aid groups have been raising the alarm of an impending famine in South Sudan for months, and instead of taking the warnings seriously, it fell largely on deaf ears," he added.

Source :AFP