In a shocking report released by the US Senate investigators, practices such as “rectal hydration” and “rectal feeding” are described. The “lunch tray” for one detainee, which contained hummus, pasta with sauce, nuts and raisins”, was pureed and rectally infused, the report says. At least five men received this form of feeding through the rectum. The report found no medical necessity for the treatment.

The detention and interrogation program was authorised by Bush six days after the terrorist attacks of 9/11. It was part of the CIA’s global counterterrorism effort to dismantle al-Qaeda and prevent another mass-casualty strike on American soil.

Bush approved the torture program through a covert finding in 2002, but he wasn’t briefed by the CIA about the details until 2006. At that time he expressed discomfort with the “image of a detainee, chained to the ceiling, clothed in a diaper and forced to go to the bathroom on himself.” Bush said in his 2010 memoirs that he discussed the program with CIA Director George Tenet, but Tenet told the CIA inspector general that never happened.

The Senate Intelligence Committee’s report found that treatment in secret prisons a decade ago was worse than the government told Congress or the public. The committee’s report also claims to debunk the CIA’s assertion that its practices led to Osama bin Laden’s killing. The agency has disputed this finding and said its interrogation of detainee Ammar al-Baluchi revealed a known courier was taking messages to and from bin Laden.

Redha al-Najar, a former bin Laden bodyguard, was the first prisoner keep at a facility called COBALT, which is understood to be the CIA’s “Salt Pit” in Afghanistan. Detainees were kept isolated and in darkness, their cells had only a bucket for human waste.

After a month of sleep deprivation, CIA interrogators found al-Najar a “broken man.” But the treatment got worse, with officials lowering food rations, shackling him in the cold and giving him a diaper instead of toilet access.

Gul Rahman, a suspected extremist, received enhanced interrogation there in late 2002, shackled to a wall in his cell and forced to rest on a bare concrete floor in only a sweatshirt. The next day he was dead. A CIA review and autopsy found he died of hypothermia. Justice Department investigations into that and another death of a CIA detainee resulted in no charges.

But the “enhanced interrogation techniques” didn’t produce the results that really mattered, the report asserts in its most controversial conclusion. It cites CIA cables, emails and interview transcripts to rebut the central justification for torture — that it thwarted terror plots and saved American lives.

The report outlines 13 torture techniques:

1. Abdominal Slap - The purpose was to cause the detainee to feel fear and despair, to punish certain behaviour and humiliate or insult the detainee, according to a description in government documents, obtained by the American Civil Liberties Union in 2009. The interrogator stands about a foot from the detainee’s stomach, and slaps the detainee with the back of his hand. The interrogator’s hand is held with the fingers together and straight and slaps the detainee’s abdomen. The CIA was using this technique prior to 2004 without approval by the Justice Department.

2. Attention Grasp - The interrogator grabs the detainee by the collar, with two hands, and pulls him closer in, according to a description of the technique by former CIA acting general counsel John Rizzo. Rizzo described this technique being used on al-Qaeda operative Abu Zubaydah in his recent book, “Company Man.”

3. Cramped Confinement - The interrogator would put the detainee in a box, sometimes big enough to stand in, for up to 18 hours, or one only big enough to curl up in for up to two hours, Rizzo said in his book. The interrogator had the option to put a “harmless” insect inside the small box when the technique was used on Zubaydah, because he hated bugs, Rizzo said.

4. Dietary Manipulation - This technique involved switching from solid foods to liquid. For instance, in August of 2002, Zubaydah was put on a liquid diet that consisted of Ensure and water, the Senate report said.

5. The Facial Hold - The interrogator holds the detainee’s head so it can’t move and puts one hand on each side of the detainee’s face, keeping fingertips away from the detainee’s eyes, Rizzo explained in his book.

6. The Facial Slap/Insult Slap - The interrogator slaps the detainee in the face, with fingers spread, striking between the chin and earlobe, Rizzo explained in his book. The idea, Rizzo said, was to startle or humiliate the detainee, Zubaydah, and “disabuse him of the notion that he wouldn’t be physically hit.”

7. Nudity - This technique was used with others. For instance, a detainee would be forced to stand for prolonged periods while nude.

8. Stress Positions - The purpose of these techniques are to stimulate mild discomfort from extended muscle use, according to a description in a government document obtained by the ACLU. Two such positions, used on Zubaydah, were to have him sit on the floor with his legs stretched out in front of him and his arms above his head, or kneeling on the floor while leaning back at a 45-degree angle, Rizzo said in his book.

9. Sleep Deprivation - Detainees were kept awake for up to 180 hours, often standing or in a stress position, the Senate report said. Sometimes, the detainees’ hands would be shackled above their heads. At least five detainees had “disturbing hallucinations” during this technique, and in two of those cases, the CIA continued the practice. One detainee, Arsala Khan, hallucinated after 56 hours of standing sleep deprivation in October 2003. After this, the CIA came to the conclusion that he ““does not appear to be the subject involved in ... current plans or activities against US personnel or facilities.” After about a month of detention and interrogation, the CIA recommended he be released to his village, but interrogators instead transferred him to the US military, where he remained in custody for four years.

10. Wall Standing - A detainee faces a wall, standing about four feet away. The interrogator has the detainee reach out his arms toward the wall so that his fingers are touching it. The detainee would have to hold that position indefinitely, according to a description by Rizzo about this technique used on Zubaydah.

11. Walling - Interrogators slam detainees against a wall. In one instance, Zubaydah was slammed against a concrete wall, the Senate report said. On March 22, 2003, al-Qaeda leader Khalid Sheikh Mohammed underwent “intense” questioning and walling. Giving up no new information, interrogators water-boarded him. After an hour of that, he said he was “ready to talk,” the CIA said.

12. Waterboarding - The detainee is strapped to a board or bench, and water is poured over the detainees face to simulate drowning. According to the Senate report, the technique brought on convulsions and vomiting, immediate fluid intake and involuntary leg, chest and arm spasms. Abu Zubaydah became “completely unresponsive, with bubbles rising through his open, full mouth.” Zubaydah was described as “hysterical” after these sessions and “distressed to a level that he was unable to effectively communicate.” At one point, Khalid Sheik Mohammad was water-boarded 65 times between the afternoon of March 12, 2003 and the morning of March 13.

13. Water Dousing - Naked detainees were held down on a tarp on the floor, according to the Senate report. The tarp would be pulled up around them to make a bathtub. Cold or refrigerated water would be poured on them. In some cases, detainees were hosed down over and over again as they were naked and shackled, standing in a sleep deprivation pose.

After reviewing six million agency documents, investigators said they could find no example of unique, lifesaving intelligence gleaned from these coercive techniques — another sweeping conclusion the CIA and Republicans contest.

The use of Enhanced Interrogation Techniques by the CIA ended in December 2007 and was later prohibited by President Barack Obama when he took office in 2009.

Obama, who ended the detention and interrogation program by executive order, said the report showed that CIA tactics had been counterproductive and contrary to American values.

“It reinforces my long-held view that these harsh methods were not only inconsistent with our values as nation, they did not serve our broader counterterrorism efforts or our national security interests,” he said.

The President also directed that the CIA no longer operate detention facilities and banned the use of all interrogation techniques that were not in the Army Field Manual.

Senate investigators accused the spy agency of inflicting pain and suffering on prisoners beyond legal limits. The CIA was also accused of creating deceptive stories about lifesaving interrogations unsubstantiated by its own records.

Committee chairman and Democrat, Senator Dianne Feinstein said: “Under any common meaning of the term, CIA detainees were tortured”.

Former CIA officials disputed the report’s findings. So did Senate Republicans, whose written dissent accuses Democrats of inaccuracies, sloppy analysis and cherrypicking evidence to reach a predetermined conclusion. CIA officials prepared their own response acknowledging serious mistakes, but saying they gained vital intelligence that still guides counterterrorism efforts.

“The program led to the capture of al-Qaeda leaders and took them off the battlefield,” said George Tenet, CIA director when the September 11, 2001, attacks occurred. He said it saved “thousands of American lives.”

Five hundred pages of the Senate report were released, representing the executive summary and conclusions of a still-classified 6,700-page full investigation. It has generated a huge response on Twitter, with many tweeting using the hashtag #TortureReport.

In a CIA fact sheet released on Tuesday, the spy agency disagreed that it had “intentionally misrepresented the program to Congress”, others in the Executive Branch and the media. However, it acknowledged, “there were instances where representations ... were inaccurate, imprecise, or fell short.”

The CIA also put forward a response in 2013 to the Senate Select Committee on Intelligence (SSCI) Study, acknowledging that the program had shortcomings and the agency made mistakes.

“The most serious problems occurred early on and stemmed from the fact that the agency was unprepared and lacked the core competencies required to undertake an unprecedented program of detaining and interrogating suspected terrorists from around the world,” a CIA fact sheet states.

“In carrying out that program, CIA did not always live up to the high standards that we set for ourselves and that the American people expect of us.

“CIA has owned up to these mistakes, learned from them, and taken numerous corrective actions over the years. Further improvements to CIA practices continue to be made today as a result of our review of the SSCI Study.”

The committee report, released after months of negotiations with the administration about what should be censored, was issued amid concerns of an anti-American backlash overseas. American embassies and military sites worldwide were taking extra precautions.

Earlier this year, Senator Feinstein accused the CIA of infiltrating Senate computer systems in a dispute over documents as relations between the investigators and the spy agency deteriorated, the issue is still sensitive years after President Obama halted the interrogation practices upon taking office.

The program was approved in 2002 after al-Qaeda operative Abu Zubaydah was arrested in Pakistan. The CIA received permission to use waterboarding, sleep deprivation, close confinement and other techniques. Agency officials added unauthorised methods into the mix, the report says.

Mr Zubaydah was held in a secret facility in Thailand, called “detention Site Green” in the report. Early on, with CIA officials believing he had information on an imminent plot, Mr Zubaydah was left isolated for 47 days without questioning, the report says. Later, he was subjected to the panoply of techniques. He later suffered mental problems.

During a waterboarding session, Mr Zubaydah became “completely unresponsive with bubbles rising through his open full mouth,” according to internal CIA records.

Khalid Sheikh Mohammed, the 9/11 mastermind, received the waterboarding treatment 183 times. Though officers noted he wasn’t becoming more compliant, they waterboarded him for 10 more days. He was waterboarded for not confirming a “nuclear suitcase” plot the CIA later deemed a scam. Another time, his waterboarding produced a fabricated confession about recruiting Black Muslims in Montana.