The secret network of black site prisons across Europe that the CIA used to interrogate "terror" suspects has had a rare public hearing at Europe's human rights court.
Lawyers for two suspects, currently held by the US in Guantanamo Bay, Cuba, accuse Poland of human rights abuses.
They told the European Court of Human Rights on Tuesday that the two fell victim to the CIA's programme to kidnap suspects and transfer them to third countries.
They also allege they were tortured in a remote Polish prison.
One of the cases concerns 48-year-old Saudi national, Abd al-Rahim al-Nashiri, who faces "terror" charges in the US for allegedly orchestrating the al-Qaeda attack on the USS Cole in 2000.
The second case involves 42-year-old Abu Zubaydah, a Palestinian.
Both men say they were brought to Poland in December 2002, where they were detained and subjected to harsh questioning in a Polish military installation in Stare Kiejkuty, a village in the country's remote northeast.
They are asking the court to condemn Poland for various abuses of rights guaranteed by Europe's Convention on Human Rights.
Former CIA officials have told the Associated Press news agency that a prison in Poland operated from December 2002 until the fall of 2003.
Human rights groups believe about eight suspects were held in Poland, including Khalid Sheikh Mohammed, the self-proclaimed mastermind of the September 11, 2001, attacks.
Polish leaders in office at the time, former President Aleksander Kwasniewski and former Prime Minister Leszek Miller denied the prison's existence.