The United Nations report found that despite intensive international efforts to halt abuses in police and intelligence questioning after a similarly troubling report in 2011, the problem had actually gotten worse, particularly in the Afghan National Police. That force’s training and rapid expansion have been overseen by Western officials.

Concerns about torture prompted NATO military forces to stop handing over battlefield detainees to Afghan officials in many places. And the broader issue of detainee transfers has been a lasting point of contention between American officials and Mr. Karzai, who has insisted on complete Afghan authority over detentions.

The international Convention Against Torture, which the United States has signed, prohibits the transfer of a detainee “to another state where there are substantial grounds for believing that he would be in danger of being subjected to torture.”

Although rights advocates saw the panel’s finding on Monday as an important first step, they expressed doubts about whether the abuses would diminish without stronger actions from the government. Both the departing allied military commander in Afghanistan, Gen. John R. Allen, and United Nations officials noted at the time the report was issued in January that they were aware of almost no cases in which Afghan officials suspected of torture had been punished or even moved.

“It is significant, because it’s the first time that the Afghan government is admitting that torture is truly a bigger problem — that it’s not just a few bad apples,” said Heather Barr, the Afghanistan researcher for Human Rights Watch. “The question is will they actually do anything about it? Are they prepared to find another way to operate?”