Story highlights The report says 136 people have been subjected to rendition

The findings were derived from public sources

Supporters say rendition was an important part of national security policy

As many as 54 countries participated in the overseas detention and rendition programs overseen by the CIA in the years following the September 11 attacks, according to a new report from a human rights watchdog group.

The report from the Open Society Justice Initiative is an extensive look at a program that has remained largely unreported in its size and scale despite official acknowledgment from former President George W. Bush and other U.S. officials.

According to the report, 136 people have been subjected to the process of rendition - the transfer of a terrorism suspect by the United States to a third country for interrogation - or have been held in one of the so-called "black site" prisons in third countries run by the CIA.

"The consequence of having so many partners engaged in these operations is that the United States is exposed to continuing embarrassment, liability and censure in multiple jurisdictions outside the United States," Amrit Singh, the report's author told CNN.

The findings were derived from public sources, including documents from U.S. and foreign governments, inquiries from the European Parliament and Council of Europe, findings from human rights investigations and news reports.

The CIA secretly held detainees at detention facilities in Lithuania, Morocco, Poland, Romania and Thailand in addition to Afghanistan and Guantanamo Bay, Cuba according to the report.

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The report said that countries as varied as Azerbaijan, Canada, Denmark, Malawi, Kenya, Zimbabwe, Malaysia and Sri Lanka also participated through their interrogation, torture or role in capturing terror suspects.

Cooperation could also include permitting the use of airspace for overflight rights of planes carrying terror suspects, the report said.

The findings also discussed reports of a secret prison in Somalia run with CIA involvement, along with a two-month secret detention of a terror suspect aboard a U.S. Navy ship.

The Italian Supreme Court last year upheld convictions of 23 Americans tried in absentia for the kidnapping of a Muslim cleric from the streets of Milan.

They were accused by prosecutors of whisking the cleric to Egypt for interrogation as part of a CIA team working with Italian intelligence officials on a terrorism investigation.

Separately, the European Court of Human Rights recently held that the government of Macedonia violated the rights of Khaled El-Masri, a German national who alleged the CIA abducted him from Macedonia and sent him for interrogation in Afghanistan as part of a terrorism investigation.

The U.S. Supreme Court had earlier refused to hear El-Masri's case, after lower federal courts rejected his legal claims.

A consequences of cases like El-Masri, according to Singh, is that "governments will be increasingly reluctant to cooperate with the United States in counter-terrorism operations that could potentially expose them to liability."

While President Barack Obama issued an executive order in 2009 disavowing the use of torture, banned the use of enhanced interrogation techniques on terrorism suspects, and ordered the closure of secret detention facilities, the order did not repudiate the practice of rendition.

"In fact, the order was specifically to permit short term detention for rendition purposes," Singh said. "Exactly how rendition is being carried out in practice still remains unclear."

Supporters of the rendition and detention programs say they were an important component of national security policy in the uncertain threat environment following the 2001 attacks.

"All of these plots, everything that was planned after 9/11 never happened," Marc Thiessen, chief speech writer for President George W. Bush told CNN. "Today, people sit back from the security of a dozen years since 9/11 and judge what the CIA. did back then. But the reality is without it, we would not have gone 12 years without a terrorist attack."

In December, the Senate Intelligence Committee voted to approve a wide-ranging report on CIA detention and interrogation policies that is still classified.

The issue is likely to be prominent at the committee's confirmation hearing for John Brennan, who has been nominated to be the next CIA director.

He characterized the practice as an "absolutely vital tool" in combating terrorism in a 2005 interview.

But critics of the administration's counterterrorism policy say increased use of armed drones against terrorism suspects, instead of interrogations, comes at the expense of important intelligence gains.

"When you send a drone to kill a terrorist, you not only vaporize the terrorist, you vaporize all the intelligence in his brain and so you might as well be setting file cabinets in the CIA on fire," Thiessen says. "The destruction of intelligence that has taken place under this administration's watch is unfathomable."