A long-simmering dispute between some senators and the CIA burst into public view Tuesday when the head of the Senate Intelligence Committee accused the spy agency of improperly searching a congressional database.
The CIA — which has accused Senate staffers of taking classified reports without permission — has referred the entire matter to the Justice Department, which Sen. Dianne Feinstein, D-Calif., called in part "a potential effort to intimidate this staff. And I am not taking it lightly."
CIA Director John Brennan denies the agency did anything wrong, and said it is cooperating with a congressional investigation into CIA detention and interrogation techniques.
Speaking from the floor of the Senate, Feinstein said she has "grave concerns that the CIA's search may well have violated the separation of powers principles embodied in the U.S. Constitution."
Brennan told NBC News that the CIA did not try to interfere with the congressional investigation of waterboarding and other interrogation techniques that took place during the administration of President George W. Bush.
"The matter is being dealt with in the appropriate way, being looked at by the right authorities and the facts will come out," Brennan said. "But let me assure you that CIA in no way was spying on the (intelligence committee) or the Senate."
The dispute centers in part on rules that the Senate and CIA had set for document collection connected to the congressional probe.
In 2009, the Senate Intelligence Committee began a review of detention and interrogation policies applied to terrorism suspects after the attacks of Sept. 11, 2001. Critics said waterboarding and other interrogation techniques amounted to torture.
The committee has not released its final report, in part because the CIA has demanded corrections.
During the process, the CIA accused the Senate Intelligence Committee of downloading certain classified internal documents without its permission, prompting its search of Senate computers without the committee's knowledge.
Feinstein says the committee was entitled to the documents, and did not take them without CIA permission.
As for allegations that Senate aides improperly obtained an internal CIA report, Feinstein said "the committee staff did not 'hack' into CIA computers to obtain these documents as has been suggested in the press." She said they identified documents using a search tool provided by the agency.
"I have asked for an apology and a recognition that this CIA search of computers used by its oversight committee was inappropriate," Feinstein said. "I have received neither."
In his NBC interview, Brennan said that "there has never been an effort by the CIA to thwart" the committee's probe into interrogation techniques.
"They have their congressional oversight responsibilities and we have worked with them over the past year on their report and we look forward to working with them in the future," Brennan said.
White House spokesman Jay Carney declined to comment on the Justice Department referral, but noted that there have been disagreements about the "protocols" for interactions between between the Senate and CIA staffs.
"There have been periodic disputes about that process," Carney said.
Carney also said that President Obama "has great confidence" in CIA Director Brennan, as well as "our intelligence community and our professionals at the CIA."
Obama ended the detention and interrogation techniques in question shortly after he took office in 2009.
Several lawmakers applauded Feinstein's comments. Sen. Mark Udall, D-Colo., a member of the intelligence committee, criticized what he called "the CIA's actions to subvert congressional oversight."
News outlets have reported that committee members believe the CIA misled Congress and other government officials over details of the program.
Referring to an initial staff report, Feinstein said that "the interrogations and the conditions of confinement at the CIA detention sites were far different and far more harsh than the way the CIA had described them to us."