Obama: I will protect the CIA

In a speech designed to boost morale at the CIA headquarters in Langley, Virginia, the president assured operatives that the identities of those involved would not be revealed.

But he said the CIA had to have higher standards in the fight against an unscrupulous enemy who "willingly and gladly kill innocents".

Mr Obama said: "What makes the United States special and what makes you special is precisely the fact that we are willing to uphold our values and our ideals even when it's hard, not just when it's easy.

"Even when we are afraid and under threat, not just when it's expedient to do so. That's what makes us different. So yes, you've got a harder job and so do I."

Four memos revealed by the Justice Department outlined harsh interrogation techniques used on suspected al Qaeda terrorists.

They included simulated drowning, waterboarding and beatings, and one suspect with a phobia of insects was put in a coffin-like space and told hundreds of bugs would be released. The memos also revealed that the alleged mastermind of the 9/11 terror attacks, Khalid Sheikh Mohammed, was subjected to waterboarding 183 times.

Former CIA directors condemned the Obama administration's release of the memos, saying the organisation had been compromised. But, following a private meeting with CIA chief Leon Panetta, Mr Obama addressed agency staff to explain his position, saying the CIA was the "tip of the spear" of America's intelligence gathering.

"You need to know that you've got my full support," he said. "For decades the American people have counted on you to protect them. I know that I've come to personally count on your services. I rely on your reporting and your analysis, which finds its way onto my desk every single day."

Explaining his decision to release the torture memos, he said much of the information had already been made public and that names of agents involved would stay secret.

"I will be as vigorous in protecting you as you are vigorous in protecting the American people," he said.

Mr Obama also said he put an end to the interrogation techniques because he believed the US was "stronger and more secure when we deploy the full measure of both our power and the power of our values, including the rule of law".

The president, making his first visit to the CIA headquarters, said he understood the problems facing the agency. "I understand that it's hard when you are asked to protect the American people against people who have no scruples and would willingly and gladly kill innocents," he said.

"Al Qaeda is not constrained by a constitution. Many of our adversaries are not constrained by a belief in freedom of speech or representation in court or rule of law. So I'm sure that sometimes it seems as if we're operating with one hand tied behind our back."

Mr Obama urged the CIA not to be discouraged by events of the last week and was applauded several times during his speech.