CIA Director John Brennan, asked about Feinstein's accusations, said the agency was not trying to stop the committee's report and that it had not hacked into Senate computers. He said the appropriate authorities would look at the matter further and "I defer to them to determine whether or not there was any violation of law or principle."
The CIA provided computers to congressional staffers in a secure room in northern Virginia in 2009 so the panel could review millions of pages of top secret documents in the course of its investigation into the CIA's detentions and interrogations during the Bush administration. At issue now is whether the CIA violated an agreement made with the Senate Intelligence Committee about monitoring the panel's use of CIA computers.
Feinstein said the Senate staff members had an electronic search tool to deal with 6.2 million pages of documents and the ability to make copies on their computers. She said the arrangement suffered a blow when CIA personnel electronically removed the committee's access to documents that had already been provided to the panel.
She said about 870 documents were removed in February 2010, and an additional 50 were withdrawn without the knowledge of the committee.
Feinstein said she has asked the agency for an apology but the CIA has been silent. CIA Director John Brennan, who first told Feinstein about the surveillance of the Senate investigation that occurred before he took over the CIA, had no immediate comment on the senator's statement.
The dispute comes as the Obama administration is trying to regain public trust after classified details about widespread surveillance of Americans were disclosed by former National Security Agency systems analyst Edward Snowden last summer.
This dispute does not involve the NSA spying on Americans, but it does show a fractious relationship between the U.S. spy agencies and the Congress charged with overseeing them.
Feinstein, as head of the Intelligence panel, has defended the NSA against criticism of its practices, making her comments about the CIA dispute highly unusual. Senators said the stakes demanded it.
"If we do not stand up for the protection of the separation of powers and our ability to do oversight, especially when conduct has happened that is all likelihood criminal conduct on the part of a government agency, then what do we stand for?" asked Sen. Patrick Leahy, D-Vt., chairman of the Judiciary Committee.
Republican Sen. Lindsay Graham of South Carolina also reflected congressional anger.
"Heads should roll, people should go to jail if it's true," Graham said. "If it is, the legislative branch should declare war on the CIA."
Saying she wanted to set the record straight amid various published reports and rampant speculation, Feinstein said the CIA searched the computer network in January and she had pressed Brennan about the agency's actions and the legal basis for its search. She said she had not received any answers despite letters sent on Jan. 17 and Jan. 23.
Feinstein said the CIA's inspector general, David Buckley, has referred the matter to the Justice Department "given the possibility of a criminal violation by CIA personnel."
In further evidence of the escalating fight, Feinstein said that after the inspector general's referral, the acting counsel of the CIA filed a criminal report with the Justice Department regarding the committee staff's actions.
Feinstein defended the staff as professionals with appropriate security clearances.