The World Bank has been accused of publishing false accounts and wasting money on ineffective medicines in its malaria treatment programme.
Malaria is spread by mosquitoes
A Lancet paper claims the bank faked figures, boosting the success of its malaria projects, and reneged on a pledge to invest $300-500m in Africa.
It also claims the bank funded obsolete treatments - against expert advice.
The bank has denied the allegations and says it is investing $500m to $1bn (£280m-£560m) over the next five years.
But it also admits it is not easy, and sometimes "not even possible", to know exactly how much input from each donor goes into a specific activity.
The claims against the bank, made by 13 international public health experts headed by Amir Attaran, of Canada's University of Ottawa, centre on the financial pledges the fund made to fight malaria on the African continent and a programme in India.
The researchers accused the bank of failing to reverse historic "neglect" of the battle against malaria and of hyping their spending on that battle in Africa.
The paper highlights a promise to lend Africa $300m-$500m for the battle against malaria.
It goes onto say that the bank appeared to backtrack, pointing to accounts that say it had earmarked $100-150m for malaria-control worldwide between 2000 and 2005.
In a rebuttal article, the bank's Jean-Louis Sarbib, says that between 2006 and 2008 $500m in expected commitments for malaria control would be spent in Africa and Asia.
The Lancet study also alleges that the World Bank hyped the results of its malaria control programme in India.
They quote the bank saying that it reduced deaths from malaria in the Indian states of Gujarat by 58%, Maharashtra by 98% and Rajasthan by 79%.
The authors say they doubted malaria could be reduced so markedly in such a short time and requested and obtained official statistics from India's own national malaria programme.
According to India's Directorate of National Vector Borne Disease Control Programme, deaths from malaria rose in all three states in the 2002-3 period in question.
"Because we were refused access to the original data sources, we cannot discern the cause of the bank's many statistical errors and particularly whether those errors arise from unintentional mistakes or from intentional data falsification or fabrication," the authors say.
But the World Bank says in its rebuttal, that the study authors were using "aggregated state-level data" that "do not tell the whole story".
"We were able to see clear measurable improvements in districts where the bank-supported malaria control project was implemented," the bank said.
The study also claims: "The bank's secrecy and technical errors combine dangerously when we look at malaria treatment.
"Our investigations suggest that the bank wasted money and lives on ineffective medicines."
It accuses the bank of supplying India with an anti-malarial drug, called chloroquine, at a cost of $1.8m, which it says is unsuitable for the type of malaria seen there and against World Health Organisation guidelines.
However, the bank argues that the drug was only to be used in the areas where chloroquine is still effective alongside more up-to-date treatments.
It says: "On the basis of available information, India stood to get good value for money by spending scarce resources wisely in accordance with local realities."
Dr Attaran and his colleagues go on to call for the World Bank to hand over the $1bn due to be invested in malaria programmes worldwide to a separate body, saying the bank's role should be reserved only for funding.
But the bank says: "World Bank Group President, Paul Wolfowitz, has put the full weight of his leadership behind the Bank's renewed commitment to malaria, with a strong emphasis on results."
A Lancet editorial says malaria accounts for 10% of Africa's disease burden and leads to $12bn in lost productivity every year.
If the World Bank is serious about being judged on results as it claims, the 2000 target of halving malaria deaths in Africa by 2010 is an "excellent opportunity for cost-effective action," it says.