A US Senate report on harsh techniques employed to interrogate "terror" suspects post-9/11 attacks has condemned the CIA for brutality and deception.

The heavily redacted 480-page report - published on Tuesday - covered the treatment of around 100 suspects rounded up by US operatives between 2001 and 2009 on terrorism charges.

The full 6,200-page report remains classified. Ahead of the publication of the report, the US had tightened security at its embassies across the globe.

CIA TECHNIQUES Water boarding (simulated drowning)

Sleep deprivation

Confinement in small places

Slapping detainees

Threatening with death

Unnecessary "rectal feeding" or "rectal hydration" WHO WAS WATER BOARDED Khalid Sheikh Mohammed, alleged 9/11 mastermind

Abu Zubaydah, al-Qaeda's "travel agent"

Abd al-Rahim al-Nashiri, alleged mastermind of 2000 attack on USS Cole

Senate Intelligence Committee chair Dianne Feinstein said the techniques used by the CIA were "far more brutal than people were led to believe" and that "coercive techniques regularly resulted in fabricated information" from detainees.

"There are those who will seize upon the report and say see what the Americans did? And they will try to use it to justify evil actions or incite more violence," said Feinstein. "We can't prevent that, but history will judge us by our commitment to a just society governed by law and the willingness to face an ugly truth and say never again."

Summary: Key findings in CIA torture probe

The report said harsh CIA interrogations produced much bad information, including a fake story about al-Qaeda recruiting African-Americans. It said the interrogations were ineffective and never produced information that led to foiling of "imminent terror threat".

The report followed a five-year investigation by the Senate Intelligence Committee into the programme. The CIA maintained the harsh techniques were effective and foiled terrorist plots.

The report said the CIA misled the public and policymakers about the programme, much of which was developed, operated and assessed by two outside contractors.

Threats and sleep deprivation

The tactics discussed in the document include threats that Abd al-Rahim al-Nashiri, a suspect in the 2000 bombing of the USS Cole, would have his mother "brought before him and sexually abused." He was also threatened with a power drill.

The report said some detainees were forced to stay awake for over a week at a time, and that several detainees suffered from "hallucinations, paranoia, insomnia and attempts at self-harm and self-mutilation."

Reacting to the report, US President Barack Obama said the CIA actions "were contrary to our values".

"I hope that today’s report can help us leave these techniques where they belong - in the past. Today is also a reminder that upholding the values we profess doesn’t make us weaker, it makes us stronger and that the United States of America will remain the greatest force for freedom and human dignity that the world has ever known," he said in a statement.

Unless this important truth-telling process leads to prosecution of the officials responsible, torture will remain a 'policy option' for future presidents. Kenneth Roth, Human Rights Watch

The enhanced interrogation programme was dismantled by Obama in 2009.