CIA Director John Brennan challenged allegations made today by a senator that the CIA hacked into computers used by staffers from the Senate Intelligence Committee, calling the notion "beyond the scope of reason."

Earlier in the day, Senator Dianne Feinstein, chairperson of the committee, took to the Senate floor to express "grave concerns" that the CIA had conducted an unauthorized search of a standalone computer network used by the committee to gain access to classified CIA documents about the agency's controversial rendition program.

In January, the CIA contacted the committee with information that it believed staffers may have gained access to documents that should not have been on that network. Senators on the committee believe the CIA was able to determine that only by violating an agreement that the CIA would not have access to the computer network.

In a lengthy and blistering speech, Feinstein said she believed the CIA may have acted illegally in conducting a search that also "may well have violated the separation of powers principles embodied in the United States Constitution."

"Besides the constitutional implication, the CIA's search may also have violated the 4th amendment, the computer fraud and abuse act, as well as executive order 12333 which prohibits the CIA from conducting domestic searches or surveillance," Feinstein said.

But Brennan refuted the accusations.

"Nothing could be further from the truth" Brennan said as he spoke before a gathering of the Council of Foreign Relation in Washington. "I mean we wouldn't do that. I mean that's just beyond the scope of reason in terms of what we would do."

In her remarks, Feinstein said she had asked for an apology "and a recognition that this CIA search of computers used by its oversight committee was inappropriate."

She added, "I have received neither."

"We are not in any way, shape or form trying to thwart this report's progression [or] release," said Brennan.

Senate Majority Leader Harry Reid backed up Feinstein at a news conference.

"I support Senator Feinstein unequivocally," Reid said. "I am disappointed that the CIA has is apparently unrepentant for what I understand they did."

The Senate Intelligence Committee has not released the exhaustive report that determined the CIA's own documents raised questions about the agency's rendition program. After 9/11, the CIA held high-level detainees at secret prisons where they were submitted to intense interrogation techniques. The program ceased operating in September 2006 when President Bush announced the transfer of 14 high level CIA detainees to Guantanamo.

On January 15, Brennan contacted Feinstein to inform her and committee's vice-chairman, Sen. Saxby Chambliss, that the CIA had recently performed a "search" of that network. That had led the CIA to determine that committee staffers had been given access to files that should not have been on the network. The Justice Department is now investigating the matter.

Feinstein said today that since then she had tried "to resolve this dispute in a discreet and respectful way, " but that the "the increasing amount of inaccurate information circulating now cannot be allowed to stand unanswered."

Last week, Brennan released a statement expressing his dismay that "some members of the Senate have decided to make spurious allegations about CIA actions that are wholly unsupported by the facts."

He encouraged lawmakers to take their time and not "overstate what they claim and what they probably believe to be the truth. These are some complicated matters."