KABUL - Afghan President Hamid Karzai's chief of staff said Saturday that he is not sure the government is "on a path to success" in securing the country against the Taliban and that it could fail altogether if the United States does not significantly alter its strategy in fighting the nine-year-old war.

In a rare extended interview, Mohammad Umer Daudzai, who usually plays a behind-the-scenes role at the presidential palace, said he was speaking out because media reports of worsening U.S.-Afghan relations are "taking up a lot of our time" and have had a damaging effect on the fight against a growing insurgency.

On Saturday morning, Taliban insurgents disguised as American soldiers attacked two U.S. bases in eastern Afghanistan and managed to breach the perimeter of one base before being repelled. The simultaneous assaults on Forward Operating Base Salerno and nearby Forward Operating Base Chapman in Khost province ended with 21 insurgents killed but no U.S. deaths, NATO officials said.

While stressing that the Karzai government is committed to a significant NATO troop presence, Daudzai called on the international forces to stop invasive night raids on residents' homes and to distance their soldiers from "the daily life of the people," a sharp divergence from Gen. David H. Petraeus's strategy of having soldiers embedded in communities. The coalition policies have undermined Karzai's authority and Afghan sovereignty, Daudzai said, and led to "blame games" between the two sides.

In a meeting with Petraeus last week, Daudzai said that he was blunt with the U.S. military commander.

"I said, 'General Petraeus, winning the hearts and minds of the Afghans is not the job of a soldier. That's the job of an Afghan,' " Daudzai said.

Daudzai described Karzai as "concerned" and committed to changing the U.S. approach to the war.

"He's putting those conditions there, that if we do not review, then we will be on the path toward losing," he said. "We need to review our strategy, our code of conduct, so that Afghans believe that this is a sovereign state and President Karzai is the ultimate decision maker in this country.. . . We are in the last stage, the last chance of winning this war. So we cannot afford to spend a lot of time on accusations and counter-accusations."

Daudzai's statements come in the wake of media reports that many of Karzai's aides have long been secretly paid by the CIA. That revelation has raised questions about the duplicity of the U.S. strategy in Afghanistan, where U.S. officials are pushing Karzai to crack down on corruption among his aides, some of whom may be collecting regular salaries from the CIA.

The Karzai administration pushed back strongly last week against growing U.S. pressure. On Monday, presidential spokesman Waheed Omer said that corruption in connection with international contracts for Afghan companies was a bigger problem than any wrongdoing within the government.

But U.S. officials have grown increasingly alarmed about Karzai's lack of progress in reforming his government, and many think official corruption has become the greatest obstacle to winning over Afghans from the Taliban. Last week, Fazel Ahmad Faqiryar, a deputy attorney general, was fired from his job, telling the New York Times that it was because he had refused to block corruption investigations of top Afghan officials.

Rangin Dadfar Spanta, Afghanistan's national security adviser, said that Faqiryar, at 72, was too old by law to hold his post. "His existence is illegal," Spanta said.