Washington (CNN) -- The chairman of the Senate Intelligence Committee accused the CIA of secretly removing classified documents from her staff's computers in the middle of an oversight investigation, while another lawmaker said Congress should "declare war" on the spy agency if it's true.
Sen. Dianne Feinstein said CIA Director John Brennan told her in January that agency personnel searched the computers last year because they believed the panel's investigators might have gained access to materials on an internal review they were not authorized to see.
"The CIA did not ask the committee or its staff if the committee had access to the internal review or how we obtained it," Feinstein said in blistering remarks on the Senate floor. "Instead, the CIA just went and searched the committee's computer."
Feinstein said that she had "grave concerns" the search may have violated federal law regarding domestic spying as well as congressional oversight responsibilities under the Constitution.
"I have asked for an apology and a recognition that this CIA search of computers used by its oversight committee was inappropriate. I have received neither," she said.
Republican Sen. Lindsey Graham of South Carolina called the allegations "dangerous to a democracy," if it's substantiated that the CIA interfered with a congressional investigation.
"Heads should roll, people should go to jail, if it's true. ... I'm going to get briefed on it. If it is, the legislative branch should declare war on the CIA, if it's true," Graham said.
Feinstein's comments pushed into the public spotlight months of behind-the-scenes wrangling over access to and the review of documents around the post 9/11 Bush administration program for handling terror suspects.
Brennan disputed Feinstein's claims relating to the committee's efforts to produce a comprehensive report on the practice that ultimately was ended by President Barack Obama in 2009.
"As far as the allegations of CIA hacking into Senate computers -- nothing could be further from the truth. We wouldn't do that. I mean that's, that's, that's just beyond the scope of reason," Brennan told the Council on Foreign Relations.
He also said that the CIA believes in congressional oversight and often has "spirited" conversations about agency techniques.
"We have made mistakes. More than a few. And we have tried mightily to learn from them," Brennan said.
Brennan said in a statement last week that he was "deeply dismayed" that some members of the Senate have made "spurious allegations about CIA actions that are wholly unsupported by the facts."
White House spokesman Jay Carney said President Barack Obama has "great confidence" in Brennan and the intelligence community.
Carney would not comment on the specifics under review by the Justice Department but said Obama supported the committee's investigation.
"The President has made clear he seeks the declassification, the findings of that report when it is completed," he said.
The top Republican on the intelligence panel, Saxby Chambliss of Georgia, said "we have some disagreements" on the facts and cautioned that improving the relationship with the CIA "is not going to happen if we throw rocks at each other."
However, Sen. John McCain, an Arizona Republican, called the allegations "disturbing" and added that "a full and complete investigation" is needed.
He also stressed that he's "never had a great deal of confidence with Mr. Brennan" and therefore has "no doubt about the politicization of Mr. Brennan," a former White House official.
The Justice Department is looking at whether to launch an investigation involving the committee's review of millions of documents at a Virginia facility and counterclaims by the CIA about Intelligence Committee staffers gaining access to things they shouldn't have seen.
Feinstein took issue with the CIA IG's referral of the case to the Justice Department as an attempt to intimidate the committee.
She said committee staff "did not hack into CIA computers to obtain these documents, as has been suggested in the press."
She said the documents were identified through a search tool provided by the CIA in order to select specific material, and that the pane would follow through with its report as planned.
The CIA viewed the committee's accessing the internal review ordered by then-Director Leon Panetta as a breach and confronted committee members about it.
The committee launched its full blown investigation after learning in an initial review that the CIA had "withheld and destroyed information about its detention and interrogation program."
This, according to Feinstein, included its decision in 2005 to "destroy interrogation videotapes over the objections of the Bush White House and the director of national intelligence."
CNN's Ted Barrett, Pamela Brown and CNN staff contributed to this report.