Aid agencies have launched an urgent appeal for $10m in aid to head off a famine in West Africa.

Several countries are at risk, particularly Niger and Chad, where harvests have fallen by roughly 30 per cent this year because of a crippling drought. Food prices have increased by nearly one-third.

Mamadou Biteye, Oxfam's regional director, said many people are resorting to desperate measures to find food.

"In parts of Chad and Niger they are digging ant holes, ant houses for grain, or eating wild fruits and leaves, or even maize that is available for poultry feeding, so it's really a very difficult situation at the moment," she said.

Chad and Niger, two of the world's poorest countries, have declared a state of emergency.

Charlie Angela reports from Niger.