CIA Director John Brennan apologized to Senate intelligence committee leaders after his inspector general found that CIA employees acted improperly when the CIA searched Senate computers earlier this year.
At the centre of the allegations is a computer system setup by the CIA that allowed members of the committee to look at documents related to post-9/11 interrogation methods.
A CIA spokesman said in an email to The Associated Press on Thursday that Brennan has convened an accountability board that will investigate the conduct of the CIA officers and discipline them, if need be.
The Justice Department has so far declined to pursue criminal charges against the employees, who searched the computers for information gathered in the course of a Senate investigation into the CIA's interrogation techniques.
The CIA inspector general concluded "that some CIA employees acted in a manner inconsistent with the common understanding reached between" the committee and the CIA in 2009 regarding access to a shared classified computer network, Boyd said.
Brennan informed Senate intelligence committee Chairwoman Dianne Feinstein and Sen. Saxby Chambliss, the senior Republican on the committee, "and apologized to them for such actions by CIA officers as described in the [inspector general's] report," Boyd said.
The development was the subject of wildly different characterizations by sources on either side of the dispute, who spoke on condition of anonymity because they were not authorized to go beyond official statements.
Senate aides familiar with the matter say the CIA used classified "hacking tools" and created a fake user account in an effort to retrieve documents the CIA believed the Senate staffers had improperly accessed.
A U.S. official familiar with the inspector general report disputed that hacking tools were used, and said that there was no malicious intent behind the CIA actions, but simply an effort to account for documents believed to have been improperly accessed.