U.S. Senator Dianne Feinstein, chairwoman of the Senate Intelligence Committee, on Tuesday accused the Central Intelligence Agency (CIA) of illegally searching computers used by her staffers investigating CIA interrogation methods, but the CIA director quickly denied the allegation.

Feinstein, the top Senate overseer and traditionally a strong defender of the U.S. intelligence community, gave a speech with more details on the Senate floor. She sharply accused the CIA of undermining congressional oversight with its search of the panel's computers during its investigation of the CIA's controversial Bush- era interrogation policies.

"I have grave concerns that the CIA's search may well have violated the separation of powers principles embodied in the United States Constitution," Feinstein said.

"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 added.

Under a 2009 agreement between the Senate panel and the CIA, the panel was allowed access to many of CIA documents related to the agency's interrogation policies that the panel had been reviewing.

Feinstein said current CIA Director John Brennan told her in January that CIA personnel searched the panel's computers last year because they believed the panel's investigators might have gained unauthorized access to materials on an internal review.

"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. "Instead, the CIA just went and searched the committee's computer."

Later on Tuesday, Brennan denied the allegations of the CIA spying on Senate computers at an event organized by Washington- based think tank Council on Foreign Relations.

"As far as the allegation of CIA hacking into Senate computers, nothing could be further from the truth. We couldn't do that." he said. "That's just beyond the scope of reason in terms of what we' d do." Endite