The C.I.A., which declined to comment for this article, has long been known to support some relatives and close aides of Mr. Karzai. But the new accounts of off-the-books cash delivered directly to his office show payments on a vaster scale, and with a far greater impact on everyday governing.





Moreover, there is little evidence that the payments bought the influence the C.I.A. sought. Instead, some American officials said, the cash has fueled corruption and empowered warlords, undermining Washington’s exit strategy from Afghanistan.





“The biggest source of corruption in Afghanistan,” one American official said, “was the United States.”..

But the C.I.A. has continued to pay, believing it needs Mr. Karzai’s ear to run its clandestine war against Al Qaeda and its allies, according to American and Afghan officials.





Payments ordinarily range from hundreds of thousands to millions of dollars, the officials said, though none could provide exact figures. The money is used to cover a slew of off-the-books expenses, like paying off lawmakers or underwriting delicate diplomatic trips or informal negotiations.





Much of it also still goes to keeping old warlords in line. One is Abdul Rashid Dostum, an ethnic Uzbek whose militia served as a C.I.A. proxy force in 2001. He receives nearly $100,000 a month from the palace, two Afghan officials said. Other officials said the amount was significantly lower.





Mr. Dostum, who declined requests for comment, had previously said he was given $80,000 a month to serve as Mr. Karzai’s emissary in northern Afghanistan. “I asked for a year up front in cash so that I could build my dream house,” he was quoted as saying in a 2009 interview with Time magazine.