WARSAW, Poland (AP) — Polish prosecutors may seek access to terror suspects detained by the U.S. at Guantanamo Bay for direct questioning as part of an investigation into whether a secret CIA prison operated here in 2002-2003, an official said Thursday.

The prosecutors would need U.S. permission to question prisoners held at Guantanamo and are weighing whether to make a request. Washington has provided little help to Poland’s investigation, which was launched in 2008, and has already denied an appeal from Warsaw for assistance in gathering evidence.