A US aid program aimed at helping foreign countries battle the AIDS epidemic saved 740,000 lives from 2004-2008, according to a US study published Tuesday.

The US President's Emergency Plan for AIDS Relief, or PEPFAR, was started by former president George W. Bush in 2003 with a five-year, $15 billion investment in global AIDS in 15 countries.

The analysis by scientists at Stanford University School of Medicine in California examined health and survival information for 1.5 million adults in 27 African countries.

The analysis found that in nine of the African countries targeted by the program, 740,000 lives were saved during a four-year span compared to countries were PEPFAR was not implemented.

"PEPFAR's success with HIV may be considered the clearest demonstration of aid's effectiveness in recent years," said the study in the Journal of the American Medical Association.

Researchers decided to study the effects of PEPFAR to gauge how well it worked and if, as some have argued, it may have been draining resources from other health priorities.

"We were surprised and impressed to find these mortality reductions," said lead author Eran Bendavid, assistant professor of medicine.

"Despite all the challenges to making aid work and to implementing HIV treatment in Africa, the benefits of PEPFAR were large and measurable across many African countries."

Prominent AIDS activists including U2 singer Bono have hailed PEPFAR for its bold approach against HIV/AIDS, with some 35 million people around the world living with the disease three decades after the epidemic emerged.

However, study authors admitted that their research had some weaknesses, including that the span of countries studied did not include Botswana, South Africa and Cote d'Ivoire due to lack of "suitable data for this analysis."

"Botswana and South Africa in particular carry a heavy HIV burden, and their omission could change PEPFAR's overall effect," said the study.

The nine "focus" countries in the study were Ethiopia, Kenya, Mozambique, Namibia, Nigeria, Rwanda, Tanzania, Uganda and Zambia.