Thousands of lives and millions of pounds were lost needlessly because of a "dangerous delay" in the response to the East Africa famine, a report has found.

A "culture of risk aversion" meant the international community failed to take decisive action on early warnings, causing a six month set-back in the relief effort.

Leading aid agencies have now hit out at governments and humanitarian organisations as the report found they were "too slow" to spend money on those in need.

According to Oxfam and Save the Children, who compiled the review, many donors wanted proof of a humanitarian catastrophe before launching action to prevent one.

A likely emergency was forecast by sophisticated early warning systems as early as August 2010 but the full-scale response was not launched until July last year, when malnutrition rates in parts of the region had gone "far beyond the emergency threshold", they found.

Their report, A Dangerous Delay, showed this only came when media coverage reached particularly high levels.

Barbara Stocking, chief executive of Oxfam, said impoverished communities were still "bearing the brunt" of a failure to mount an effective response.

"We all bear responsibility for this dangerous delay that cost lives in East Africa and need to learn the lessons of the late response," she said.

"It's shocking that the poorest people are still bearing the brunt of a failure to respond swiftly and decisively.

"We know that acting early saves lives but collective risk aversion meant aid agencies were reluctant to spend money until they were certain there was a crisis."

Oxfam and Save the Children are calling on governments to overhaul their response to food crises.

Their analysis shows that under the current system, large scale emergency work is funded only when hunger levels reach tipping-point - when lives have already been lost and the cost of the response is much greater.

They have now urged organisations to seek more funding and release this as soon as the crisis signs are clear.

Justin Forsyth, chief executive of Save the Children, said the suffering of thousands of youngsters could have been avoided with "more money when it really mattered".

"We can no longer allow this grotesque situation to continue; where the world knows an emergency is coming but ignores it until confronted with TV pictures of desperately malnourished children," he added.

Estimates suggest between 50,000 and 100,000 lives were lost between April and August, with more than half of that number under the age of five.

The charities have urged governments around the world to sign up to the Charter to End Extreme Hunger, a joint-agency initiative which urges nations to take concrete steps to prevent future catastrophic disasters.