Campaigners are calling for developed countries' debt repayments to be cut to free up more money to fight Aids.

A report from Oxfam, presented to the International AIDS Conference in Barcelona said the level of repayments the countries are expected to hamper their efforts to contain the disease.

Thirteen million people with Aids live in countries classified as being heavily in debt.

Oxfam found that even after they had received debt relief, average repayments to creditors still absorbed 15% of government revenue.

What's affordable should be based on some sort of assessment of human need

Kevin Watkins, Oxfam

The charity is calling for a ceiling of 5% on the amount allocated to debt repayments.

It says the level should be even lower for countries with financial difficulties in dealing with HIV/AIDS.

Oxfam estimates this move would mean another $1.6bn would be available for spending on HIV/Aids each year.

Limit

Thirteen countries, including some of those with the highest HIV positive rates in the world, spend more on debt repayments than health.

One such country is Zambia, where almost one million people are infected with HIV and which has increasing levels of child and maternal mortality.

It spends 30% more on debt than on health.

In Cameroon, debt repayments are three-and-a-half times the figure spent on health.

Kevin Watkins, author of the report, told BBC News Online said: "Countries are spending more on debt repayment than on health or primary education."

He added: "What's affordable should be based on some sort of assessment of human need. It should not be what countries are able to pay based on what they can afford if pushed to the limit."

Mr Watkins said: "It is morally outrageous that financial claims by some of the world's richest countries are reinforcing the link between HIV/AIDS and poverty in the world's poorest countries.

Godfrey Sikipa, who has responsibility for UN HIV policy in eastern and southern Africa, said the best solution would be to cancel remaining debt completely.

He said: "We need to break the vicious cycle between economic problems and HIV."

Treatment access

Derek Bodell, chief executive of the National Aids Trust said: "Some countries, particularly in Africa, are losing so many teachers as a result of Aids that they are training three times as many as they would otherwise need to."

He backed calls for lower debt repayments, but said that had to be part of a wider range of measures.

"Vaccination development, relieving debt and access to treatment - all of these things need to be on-going.

"If you reduce the debt, but then expect the countries to pay for antiretroviral drugs that they cannot afford, then you're not breaking the cycle."