The UN Working Group on Arbitrary Detention has accused the US and seven other countries of unlawfully torturing and detaining a Saudi prisoner now in Guantanamo.
The Panel suggested that the systematic use at Guantanamo of suspects arrested during Washington's "war on terror" after the September 11, 2001 attacks, may in some cases amount to crimes against humanity.
The five independent experts in this task force addressed a case brought by Abd al-Rahim al-Nashiri, a Saudi citizen of Yemeni origin suspected of masterminding the suicide bombing of the USS Cole missile destroyer in October 2000, which killed 17 sailors.
In the case filed with the task force last June, lawyers confirmed that after al-Nashiri was arrested in Dubai in 2002, he was transferred over four years between different secret CIA sites in Afghanistan, Lithuania, Morocco, Poland, Romania and Thailand, where he was tortured and ill-treated.
He arrived at Guantanamo Bay in 2006, where he remained in detention.
He was only charged in 2008 and his death penalty case before the military commission is still pending pre-trial proceedings.
In an opinion adopted late last year, but not made public until Friday, the UN task force decided that all eight countries were "jointly responsible for torture and cruel, inhuman and degrading treatment of al-Nashiri."
According to the working group, "the memos stating that al-Nashiri was tortured are irrefutable," noting that it concluded that the eight countries were all responsible for his "arbitrary arrest, extradition and detention." Sylvain Savolanin, al-Nashiri's lawyer, described the decision as "very strong and important".
The working group, made up of five independent experts, called on the eight countries to "take the necessary steps to rectify the status of the publisher without delay."