A suspected high-ranking Al Qaeda figure held at the US naval base at Guantanamo Bay could provide limited evidence about his torture at the hands of the CIA.
Abu Zubaydah, a Palestinian, was captured in 2002 in Pakistan and has since been held by the US at the detention camp in Cuba without charges.
He repeatedly underwent waterboarding, a form of simulated drowning widely considered torture.
Earlier this month, US Supreme Court justices questioned why the US government would not let the detainee give evidence.
In response to questions from three justices during oral arguments earlier this month, acting US Solicitor General Brian Fletcher wrote a letter to the court on Friday informing the justices that Mr Zubaydah could provide a declaration in the pending case.
“Nonetheless, the government would permit Abu Zubaydah, upon his request, to send a declaration that could then be transmitted to the Polish investigation,” Mr Fletcher wrote in the letter, according to a Reuters report on Sunday.
However, he said any information could be subject to redaction if it might “prejudice the security interests of the US”.
Poland is believed to be the location of a “black site” where the CIA used harsh interrogation techniques against Mr Zubaydah.
Mr Zubaydah, now 50, has spent 15 years at Guantanamo and is one of many detainees still held there. He lost an eye and underwent waterboarding 83 times in a month while held by the CIA, US government documents showed.
He was “an associate and long-time terrorist ally of Osama bin Laden”, the leader of the Al Qaeda militant group who was killed by US forces in Pakistan in 2011, a Justice Department filing said earlier.
Mr Fletcher said in his letter that Mr Zubaydah's evidence would not resolve the dispute that is currently before the justices concerning the scope of the “state secrets” privilege, a legal doctrine available to the government to protect information that it says may threaten national security.