About $18 billion US a year has been drained from Africa by nearly two dozen wars in recent decades, a new report states, a price some officials say could have helped solve the AIDS crisis and created stronger economies in the world's poorest region.

"This is money Africa can ill afford to lose," Liberian President Ellen Johnson Sirleaf wrote in an introduction to the report by the British charity Oxfam and two groups that seek tougher controls on small arms, Saferworld and the International Action Network on Small Arms.

"The sums are appalling: the price that Africa is paying could cover the cost of solving the HIV and AIDS crisis in Africa, or provide education, water and prevention and treatment for tuberculosis and malaria," Sirleaf added.

"Literally thousands of hospitals, schools and roads could have been built."

That war makes economies suffer is nothing new, but few have tried to estimate the real cost across Africa.

Compared to peaceful countries, war-battered African nations have "50 per cent more infant deaths, 15 per cent more undernourished people, life expectancy reduced by five years, 20 per cent more adult illiteracy, 2.5 times fewer doctors per patient and 12.4 per cent less food per person," the report estimates.

On average, the economies of African countries affected by armed conflict contracted by 15 per cent and the impact generally worsened the longer a war lasted, the report said.

The report based its figures on the ill effects on economic growth by estimating what growth might have been in countries if they had not suffered conflicts. During Guinea-Bissau's 1989-99 war, for example, projected growth was five per cent, but the economy decreased 10 per cent, it said.

"This methodology almost certainly gives an underestimate," the group said in a joint statement.

"It does not include the economic impact on neighbouring countries, which could suffer from political insecurity or a sudden influx of refugees. The study only covers periods of actual combat, but some costs of war, such as increased military spending and a struggling economy, continue long after the fighting has stopped."

'Massive waste of resources'

The report looked at 23 African countries that had wars between 1990 and 2005, estimating the fighting cost a total of about $300 billion.

"This is a massive waste of resources — roughly equivalent to total international aid to Africa from major donors during the same period," the report said.

The report did not include Somalia, which has been in a state of anarchy and war since a dictatorship was overthrown in 1991 but for which no statistics were available.

The group blamed the availability of small arms for fuelling fighting in Africa. It said about 95 per cent of the weapons used in African wars — mostly the ubiquitous Kalashnikov automatic rifle — are imported from outside the continent.