The head of the CIA has apologised to US politicians after an investigation confirmed claims that his officers had "improperly" accessed Senate computers, the agency says.
In March, CIA Director John Brennan dismissed allegations the agency had spied on Senate intelligence committee investigators probing possible torture, insisting: "Nothing could be further that the truth."
But on Thursday, in an abrupt climb down, the US intelligence agency confirmed that a review by its own inspector general had confirmed that officers had indeed acted beyond their authority.
A spokesman said Brennan had met Senate Select Committee on Intelligence Chairwoman Senator Dianne Feinstein and her deputy "and apologised to them".
The scandal centres around a computer archive, RDINet, set up by the CIA in a secure building in Virginia to make classified documents available to Senate officials investigating allegations that the agency tortured prisoners between 2002 and 2006.
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In March, Feinstein furiously accused the CIA of penetrating this network during the Senate investigation, an apparent breach of the US Constitution's separation between the legislative and executive arms of government.
On Thursday, the agency admitted "some CIA employees acted in a manner inconsistent with the common understanding reached between SSCI and the CIA in 2009 regarding access to the RDINet".
CIA spokesman Dean Boyd said a new inquiry - an "accountability board" with the power to discipline officers - would be forced under the chairmanship of former senator Evan Bayh.
