Oxfam said governments and aid groups had  ignored long-term issues of crop insecurity, uneven infrastructure and inadequate social safety nets in favour of food aid that often came too late to help.

Barbara Stocking, an Oxfam director, said in a statement: "It will cost the world far less to make a major investment now in tackling the root causes of hunger than continuing the current cycle of too little, too late that has been the reality of famine relief in Africa for nearly half a century."

Last year, meagre rains and a locust plague destroyed crops across much of West Africa, causing a food emergency in countries such as Niger, Mali and Mauritania.

The region received food donations only after months of pleas from the United Nations and a concerted media campaign.

Niger worry

This year, Niger is once again facing a sparse harvest, and a prolonged drought in East Africa is causing millions to go hungry there.

The report, Causing Hunger: An overview of the food crisis in Africa, says the average number of food emergencies on the continent has almost tripled since the mid-1980s, despite two decades of effort.

The document argues that food donations, while important in an emergency, should not be "the inevitable default response to food insecurity."

Oxfam has said it typically takes up to five months to deliver food, most of which is imported and costs as much as 50% more than food bought locally.

The group urged foreign governments to concentrate on such issues as violent conflicts, Aids and climate change that can lead to food scarcity.