As the outcry grows over its now-defunct brutal interrogation program, America's spy agency appears caught in the crossfire of debate over its methods in the ongoing US battle against Islamic militants and whether it has changed its ways.

Inside the Central Intelligence Agency, intelligence officials expressed resentment over what they said was the unfairness of a Senate Intelligence Committee report released on Tuesday that harshly criticised the spy agency's detention and questioning of militant suspects.

As Senate Democrats urged more information about the program be made public and CIA officials be held accountable, CIA Director John Brennan was scheduled to speak privately to the agency's employees on Wednesday about the Senate report.

Brennan, who is close to US President Barack Obama, on Tuesday acknowledged the agency made mistakes, but rejected some key Senate panel findings, including its conclusion that harsh interrogation techniques did not produce valuable intelligence about militants that could not be obtained by other means.

"CIA is frequently asked to do difficult, sensitive and sometimes risky things on behalf of the country," a US intelligence official said. "Congress doesn't do massive studies of CIA's successful efforts such as preventing another massive casualty attack on the United States."

"The intellectual dishonesty of the (Senate) report will eventually be revealed and in the end CIA's position about the value of the detention and interrogation program will stand as the historical fact," the intelligence official said.

Countries that cooperated with the CIA's post-September 11, 2001 detention and interrogation program expressed dismay that its details became public.

"Who now in any form is going to want to continue cooperation in the fight with global terrorism and with opponents of our world view, democracy, in this domain when the system is so dramatically liable to leak?" Polish Deputy Prime Minister Janusz Piechocinski told Poland's TVN24 broadcaster.

Poland has acknowledged allowing the CIA to operate a secret interrogation center on its territory.

As details of the CIA program dribbled out over the years, the agency has faced Justice Department investigations - no prosecutions materialised - and worried it would lose cooperation from allied intelligence services.

But even some who are sympathetic to the CIA say the agency bears the brunt of blame for the damage.

"It's just a self-inflicted wound of the worst kind," said former CIA Inspector General Frederick Hitz.

TUG OF WAR

In the continuing tug of war over the CIA program, retiring Senator Mark Udall, Colorado Democrat, took to the US Senate floor to disclose findings of an earlier CIA review that he said backs up the Senate Intelligence Committee majority report.

The conclusions of the CIA study, known as the "Panetta Review" after former CIA director Leon Panetta, "fly directly in the face of claims made by senior CIA officials past and present," Udall said, urging its declassification.

He called for new legislation banning coercive interrogation techniques.

CIA officials have said the Panetta Review was not an investigation that reached conclusions, but merely a factual account of the program's history.

Significant new limits on the CIA's role and powers seem unlikely. Obama has placed the agency at the forefront of battling Islamic militants worldwide, including using armed drones.

Obama is known to rely heavily on the counsel of Brennan, formerly his top White House counter-terrorism advisor. And the CIA faces a more sympathetic Congress next year, when Republican Senator Richard Burr, who was critical of the 'torture" report, replaces Democratic Sen. Dianne Feinstein as chair of the Senate Intelligence Committee.

COULD IT HAPPEN AGAIN?

Obama in 2009 issued an executive order barring the CIA from operating detention facilities and conducting "enhanced interrogation."

The CIA on Tuesday said it had already taken steps to address issues raised in the report, including better management of sensitive programs and enhanced vetting of CIA officers who participate in them.

Philip Zelikow, who as a top State Department official in 2006 wrote a secret memo arguing some of the CIA techniques were unconstitutional, said the CIA's assurances were insufficient.

The Senate report "does raise some important issues regarding the management of covert activities", he said.

The report "will have for some time, and some time can mean for years, a chastening effect. But over time the agency does what it does," said Glenn Carle, a retired CIA officer who questioned prisoners after 2001.

"I think generations will forget," he said. "And the institution strives to serve the executive. And there will be mistakes again."