Europe's top human rights court says Poland allowed the CIA to detain two terrorism suspects at a secret prison on its territory where they were exposed to "torture and inhuman or degrading treatment".
In a 400-page ruling, the European Court of Human Rights said that Poland violated the European Convention on Human Rights and failed to properly investigate what had happened to Abd al Rahim al Nashiri, a Saudi national, and Abu Zubaydah, a Palestinian born in Saudi Arabia, while they were in CIA custody.
The CIA brought a number of suspected al Qaeda members to the prison, including Zubaydah, Nashiri and Khalid Sheik Mohammed, the self-admitted mastermind of the September 11, 2001, attacks.
While imprisoned on a military base in northern Poland, a pair of CIA contractors waterboarded Mohammed 183 times.
A CIA operative also subjected Nashiri to a mock execution and put a drill to the head of the blindfolded man, according to several former CIA officials and a report by the agency's inspector general.
"For all practical purposes, Poland had facilitated the whole process, had created the conditions for it to happen and had made no attempt to prevent it from occurring," the court said in the first judicial ruling on the rendition and interrogation programme created by the administration of President George Bush after the 9/11 attacks.
The decision is a victory for human rights advocates who petitioned the court in Strasbourg, France, to hold Poland accountable for its role in helping the CIA establish the secret prison - code-named "Quartz" - on a Polish military base in December 2002.
The court's decision rested on declassified US documents, media reports and other information that described CIA activities in Poland.
The court decision comes as the CIA braces for the release of an exhaustive study of the agency's rendition, detention and interrogation programme prepared by the US Senate Select Committee on Intelligence.
Lawmakers have said the CIA misled them about the programme's effectiveness.
The prison in Poland was closed in September 2003, with the CIA scattering the remaining detainees to sites in Morocco and Romania.
In September 2006, the agency moved Zubaydah, Nashiri, Mohammed and other 13 high-value detainees to the US prison camp at Guantanamo Bay, Cuba.
Mohammed and Nashiri are separately facing military commission trials for their alleged respective roles in the 9/11 attacks and the 2000 attack on the USS Cole in the port of Aden, Yemen.
Zubaydah continues to be held without charge in a top-secret facility at Guantanamo where the high-value detainees are held.
US officials have backed away from claims that he was a high-ranking member of al Qaeda but say he was facilitator for militants going to camps in Afghanistan.
The court ordered Poland to pay US$175,000 (NZ$204,270) to Zubaydah and US$135,000 to Nashiri.
"We are still studying the decision, but it is obviously an historic judgment that vindicates what we have said for years and now can no longer be denied," said Joseph Margulies, Zubaydah's attorney.
"The CIA ran a black site prison in Poland, with the full knowledge and complicity of the Polish government, where Abu Zubaydah was brutally tortured."
Amrit Singh, a lawyer at the Open Society Justice Initiative, who represented Nashiri before the court, also praised the decision.
"This is a historic ruling by the European Court of Human Rights, which has become the first court to confirm the existence of a secret CIA torture centre on Polish soil between 2002 and 2003, where our client Abd al Rahim al Nashiri was held and tortured," she said.
The CIA declined to comment, as did the State Department.
Poland's Foreign Ministry said it could not immediately comment because its legal experts still needed to examine the ruling, according to the Associated Press, and officials in Warsaw said it has not yet been decided whether to appeal the ruling to the Grand Chamber of the Court.
But the office of President Bronislaw Komorowski called the judgment "embarrassing" to Poland, the AP reported.
The CIA paid Poland's intelligence officials US$15 million in the winter of 2002 after they agreed to host the facility, according to former intelligence officials, who previously spoke on the condition of anonymity to discuss a classified program.
The prison was located in a cramped dacha on the base and had space for several prisoners.
The prison was under CIA control and Polish officials didn't have access to the prisoners or the ability to question them, the officials have said.
The court said it was "unlikely that the Polish officials had witnessed or known exactly what happened inside the facility".
- Washington Post