Detainees tortured at the hands of the CIA were subjected to a series of "enhanced interrogation techniques" which were far more brutal than previous feared.

According to a report released by the Senate Intelligence Committee, the CIA carried out torture techniques on terror suspects in the wake of 9/11 while misleading the nation with narratives of life-saving interrogations.

The report revealed how all of the "enhanced interrogation techniques" failed to bring any intelligence of an immediate threat.

President Barack Obama spoke of how these techniques are inconsistent with the values of the US.

"These techniques did significant damage to America's standing in the world and made it harder to pursue our interests with allies and partners," he said.

"I hope that today's report can help us leave these techniques where they belong, in the past."

Among the methods used by the CIA on terror suspects include extreme sleep deprivation, carrying out mock executions, "rectal dehydration" and waterboarding.

One suspect even died of hypothermia after he was chained naked to the floor inside the detention centre known as the Colbat or Salt Pit.

The report states how beginning with their first detainee Abu Zubaydah, the CIA applied its enhanced interrogation techniques with "significant repetition for days or weeks at a time".

It adds techniques such as slaps and 'wallings' (slamming detainees against a wall) were used in "combination [and] frequently concurrent with sleep deprivation and nudity".

The report says at least five detainees were subjected to "rectal feeding" or "rectal hydration" a procedure that the chief of interrogations would later characterise as illustrative of the interrogator's "total control over the detainee".

The report states during one incident, detainee Majid Khan had his lunch tray consisting of hummus, pasta with sauce, nuts, and raisins purified before it was rectally infused.

Others received "ice baths" and death threats. CIA officers also threatened to kill the children of detainees, rape the mother of one man and cut the throat of another's mother.

Gul Rahman, a suspected extremist, received enhanced interrogation late 2002, which included being shackled to a wall in his cell in only a sweatshirt. The next day he was dead. A CIA review and autopsy found he died of hypothermia.

No one was ever charged with his death following an investigation.

The report adds how one al-Qaida operative, Abu Zubaydah, became "completely unresponsive, with bubbles rising through his open, full mouth" during a waterboarding session. Another suspect, Khalid Sheikh Mohammed, was waterboarded at least 183 times during his detention, which the Senate report describes as escalating into a "series of near drownings."

Extreme sleep deprivation was also used on some suspects, some being forced to stay awake for more than a week.

The report states: "Sleep deprivation involved keeping detainees awake for up to 180 hours, usually standing or in stress positions, at times with their hands shackled above their heads. At least five detainees experienced disturbing hallucinations during prolonged sleep deprivation and, in at least two of those cases, the CIA nonetheless continued the sleep deprivation."

Introducing the report Intelligence Committee Chairwoman Dianne Feinstein described the CIA's actions as a "stain on US history".

"The release of this 500-page summary cannot remove that stain, but it can and does say to our people and the world that America is big enough to admit when it's wrong and confident enough to learn from its mistakes."