Published in December, the summary of the report by the US Senate's Intelligence Committee was redacted and did not mention Poland by name, but other facts in it pointed to the country and a secret CIA prison there from 2002-2003, where terror suspects were submitted to harsh treatment.
Piotr Kosmaty, spokesman for the Appeals Prosecutor's Office in Krakow that is doing the investigation, said that Poland immediately asked the US justice authorities for a full version of the document, but has had no response.
"This is undoubtedly hampering the investigation," Kosmaty told The Associated Press.
Human rights groups, European officials and media have reported there were CIA "black sites" in Poland, Romania and Lithuania.
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The European Court of Human Rights ruled last year that Poland violated the rights of terror suspects Abu Zubaydah and Abd al-Rahim al-Nashiri by allowing the CIA to imprison them and by failing to stop the "torture and inhuman or degrading treatment" of the inmates.
The US report prompted Polish leaders at the time, Aleksander Kwasniewski and Leszek Miller, to admit, after years of denials, that they authorised a prison, but not torture.
"We are continuing our investigation and waiting patiently with the hope that the US will provide the requested assistance," Kosmaty said.