Aid agencies on Monday appealed for 14 million pounds (21 million dollars, 17 million euros) to halt an escalating food crisis in West Africa, warning the situation was "an unfolding disaster."

Oxfam and Save the Children are asking for donations that total seven million pounds each as more than 10 million people across the region face severe hunger and malnutrition because of drought and crop failures.

Niger is at the epicentre of the crisis, with more than seven million people -- almost half the population -- facing food insecurity, said Oxfam.

People in Chad, Mali, Mauritania, parts of Burkina Faso and northern Nigeria are also at risk, said the charity.

Up to 380,000 children under the age of five in Niger were at risk of dying of starvation because of the unexpectedly long drought, said Save the Children.

Oxfam documented instances of people in Niger and Chad living off wild fruits, leaves and maize meant for feeding poultry, while women in Chad were digging up anthills to eat grains the ants had stored up.

"We are witnessing an unfolding disaster which can be averted if we act quickly," said Mamadou Biteye, who heads Oxfam's work in West Africa.

"The next harvests are several months away and people are already desperate. People are eating leaves and drinking dirty water.

"Unless we can raise money for this, we will be forced to turn our backs on those most in need."

Oxfam welcomed the funding it had received so far but described the response from governments around the world as "woefully inadequate."

In Niger, Chad and Mali, Oxfam said its work included distributing food, seeds and animal feed to vulnerable families, vaccinating animals and giving people paid work.

Its appeal launched Monday is to help more than 800,000 of the most vulnerable people.

Save the Children said it needed extra funding to "scale up its work in the country (Niger) and provide more families with life-saving food and medical treatment."