Reporters of Polish Television and the Rzeczpospolita daily said the evidence included documents and witness statements that were part of a Polish judicial investigation to determine whether the alleged CIA prison undermined the country's sovereignty, the EUobserver reported Wednesday.
The journalists said the Polish government in December 2001 reportedly leased a section of the Stare Kiejkuty military base in northwest Poland to the CIA, and assigned 20 secret agents to assist U.S. officials in anti-terrorist activities.
U.S. planes began secret flights to the Szymany airport close to the military base in December 2002 and at least five planes landed in Szymany in 2003.
A witness giving evidence to the Polish investigation reportedly said in 2003 he spotted people, handcuffed and blindfolded, being led from a plane.
In previous years, the European Commission and the Council of Europe accused Poland of collusion but found no hard evidence to sanction alleged human rights violations, EUobserver said.
Celebrity Breakups and divorces of 2014 [PHOTOS]