Confidential documents obtained by The Associated Press show that a leading global health fund believes that millions of dollars worth of its donated malaria drugs have been stolen in recent years, much more than it had previously discovered.

The internal investigation by the Global Fund to Fight AIDS, Tuberculosis and Malaria suggests hundreds of millions of dollars worth of the drugs may have been stolen, although it confirms the theft of only $2.5 million worth of medicine.

The reports were provided to AP by an official with a different health organization, who did so on condition of anonymity because he was granted confidential access to the documents. Global Fund spokesman Jon Liden confirmed the broad outlines of the documents.