Congressional aides involved in preparing the Senate Intelligence Committee’s unreleased study of the CIA’s secret interrogation and detention program walked out of one of the spy agency’s top-secret facility with classified documents that the CIA contended they weren’t authorized to have, McClatchy has learned.

After the CIA confronted the panel in January about the removal of the material last fall, panel staff concluded that the agency had monitored computers they’d been given to use in a high-security CIA research room in Northern Virginia, a McClatchy investigation found.

It remained unclear Wednesday if the monitoring, the unauthorized removal of classified material or another matter were the subject of a recent CIA request to the Justice Department for an investigation into alleged malfeasance in connection with the committee’s top-secret study.

The documents removed from the agency included a draft of an internal CIA review that at least one lawmaker has publicly said showed that agency leaders misled the Intelligence Committee in disputing some of the committee report’s findings, according to a knowledgeable person who requested anonymity because of the matter’s extraordinary sensitivity.

In a combative statement issued Wednesday evening, CIA Director John Brennan chastised unidentified senators for making “spurious allegations about CIA actions that are wholly unsupported by the facts.”

“I am very confident that the appropriate authorities reviewing this matter will determine where wrongdoing, if any, occurred in either the executive branch or legislative branch,” he said in an apparent reference to the request for a Justice Department investigation. “Until then, I would encourage others to refrain from outbursts that do a disservice to the important relationship that needs to be maintained between intelligence officials and congressional overseers.”

The removal of the documents is the focus of an intense legal dispute between the CIA and its congressional overseers, said several people who also cited the matter’s sensitivity in asking to remain anonymous.

Some committee members regard the monitoring as a possible violation of the law and contend that their oversight powers give them the right to the documents that were removed. On the other hand, the CIA considers the removal as a massive security breach because the agency doesn’t believe that the committee had a right to those particular materials.

“Even if the agency is technically correct on the legalities, it’s a real asinine thing to pick a fight with your oversight committee like this,” said a U.S. official who was among those who spoke to McClatchy. “You’ve got to be asking yourself why the agency would be willing to take such a risk. The documents must be so damned loaded.”

White House officials have held at least one closed-door meeting with committee members about the monitoring and the removal of the documents, said the first knowledgeable person.

White House officials were trying to determine how the materials that were taken from the CIA facility found their way into a database into which millions of pages of top-secret reports, emails and other documents were made available to panel staff after being vetted by CIA officials and contractors, said the knowledgeable person.

The extraordinary battle has created an unprecedented breakdown in relations between the spy agency and its congressional overseers and raises significant implications for the separation of powers between the legislative and executive branches of the government. It also has fueled uncertainty over how much of the committee’s report will ever be made public.

“The CIA has gone to just about any lengths you can imagine to make sure that the detention and interrogation report won’t be released,” said Sen. Mark Heinrich, D-N.M., a Senate Intelligence Committee member who has pushed hard for the release of the report.

“As furious as I am about these allegations, I want to keep focused on getting that report out to the people so that they can read the truth and make up their own minds as to who made those decisions and why,” he said.

The committee has the legal power to decide through a simple majority vote to release whatever portions of the study it deems should be made public. If the executive branch continues to resist the release of the information, the committee’s action must then be approved by the full Senate.

In voting in December 2012 to approve the final draft, the panel gave the CIA three months in which to respond to the findings and recommend what parts should be kept secret. It has now been 15 months since the committee approved the report.

Senate Intelligence Committee Chairwoman Dianne Feinstein, D-Calif., declined to comment while speaking to reporters on Capitol Hill except to confirm that CIA Inspector General David Buckley was looking into whether the agency had monitored her staff’s computers.

White House spokesman Jay Carney declined to comment, referring questions to the Justice Department and to the CIA.

“As a general matter, we are in touch with the committee,” Carney said, adding that the White House has told Feinstein that “the summary and conclusions” of the panel’s report “should be declassified with any redactions necessary to protect national security.”

While eating lunch during a visit to New Britain, Conn., with four New England governors, Obama was asked by a reporter if he had any reaction to the allegation that the CIA monitored Intelligence Committee computers.

“I’m going to try to make sure I don’t spill anything on my tie,” he responded.

The 6,300-page report lays out in exhaustive detail what lawmakers have publicly described as a scathing indictment of the CIA’s use during the Bush administration of waterboarding and other harsh techniques to interrogate suspected terrorists detained in secret “black site” prisons overseas.

The study, which took four years to complete at a cost of $40 million, also found that the CIA misled the White House, Congress and the public over the value of the intelligence produced by the program, according to the lawmakers.

Many experts and foreign governments have condemned the techniques as torture. The Bush administration, which insisted that the techniques were legal, shut down the program in 2006 and Obama banned the use of waterboarding – which he described as torture – after assuming office in 2009.

The CIA disputed significant portions of the committee’s findings in its official response to the report, which it submitted in June, three months after the deadline set by the committee. The agency also disputes that it conducted an internal review of the detention and interrogation program, asserting that it only compiled summaries of documents provided to the committee and not an analytical report.

Several months after the CIA submitted its official response to the committee report, aides discovered in the database of top-secret documents at a secret CIA facility a draft of an internal review ordered by former CIA Director Leon Panetta of the materials released to the panel, said the knowledgeable person.

They determined that it showed that the CIA leadership disputed report findings that they knew were corroborated by the so-called Panetta review, said the knowledgeable person.

The aides printed the material, walked out of the CIA facility with it and took it to Capitol Hill, said the knowledgeable person.

“All this goes back to what is the technical structure here,” said the U.S. official who confirmed the unauthorized removal. “If I was a Senate staffer and I was given access to documents on the system, I would have a laptop that’s cleared. I would be allowed to look at these documents. But with these sorts of things, there’s generally an agreement that you can’t download or take them.”

The CIA discovered the security breach and brought it to the committee’s attention in January, leading to a determination that the agency recorded the staffers’ use of the computers in the high-security research room, and then confirmed the breach by reviewing the usage data, said the knowledgeable person.

Sen. Mark Udall, D-Colo., a member of the Intelligence Committee who has led calls for the release of the report, disclosed at a hearing in December the existence of the Panetta review without saying how the committee had learned of it. He contended that the review broadly corroborated the committee’s findings and questioned why it was dramatically different from the CIA’s official response.

Udall repeated his contentions in a letter that he sent Tuesday to Obama in which he called on the president to remove from the CIA and give to the White House control over how much of the committee report should be made public.

“This internal CIA review corroborates some of the important findings of the committee study and acknowledges significant mistakes and errors made during the course of the CIA program – mistakes and errors that the CIA’s official June 27, 2013, response to the committee study denies or minimizes,” Udall wrote.

Udall also appeared to refer in the letter to the computer monitoring, writing that Obama knew that the “CIA has recently taken unprecedented action against the committee in relation to the internal CIA review.”

Udall and Heinrich have called on the CIA to submit the completed Panetta review to the committee, and Udall says he will maintain a procedural hold on the nomination of Caroline Krass to be the new CIA general counsel until the document is provided.

CORRECTION:

This story initially gave the wrong location for a high-security research room used by the committee's staff. The room was not at the CIA headquarters in Langley, Va., but was in a secret CIA facility elsewhere in Northern Virginia.

Sean Cockerham, David Lightman and James Rosen of the Washington Bureau contributed.