Improved health facilities have halved child mortality and expanded basic health services to nearly 60 percent of Afghanistan population of more than 25 million — compared to less than 10 percent in 2001.

But donors have become wary of corruption-busting pledges that have not always been delivered. Some highly placed Afghan officials have been investigated for corruption but seldom prosecuted, and some of the graft investigations have come close to the president himself.

The stakes are high as President Hamid Karzai faces international weariness with the war and frustration over his failure to crack down on corruption more than a decade after the U.S. invasion that ousted the Taliban.

Afghanistan has received nearly $60 billion in such aid since 2002. The World Bank says foreign aid makes up nearly the equivalent of the country's gross domestic product.

Those funds, which are needed