According to current and former U.S. counterterrorism officials, some European governments were informed of at least some of the details of the CIA flight operations before or as they happened. Other European governments operated what one U.S. counterterror official acknowledged amounted to a “don’t ask, don’t tell” policy regarding the CIA airplanes. In other words, the governments may have been aware that something was going on in their airspace with CIA aircraft, but they did not really want to know what was happening, did not ask too many (or perhaps any) questions about the agency’s activities, and the United States did not volunteer any answers. A CIA spokesman declined to comment.
Because the European governments themselves either had some knowledge of the CIA activities, or, in other cases, may have ignored activities they had reason to suspect were going on, some European investigators believe that the nations that allowed CIA flights to use their airfields won’t be eager to answer any questions.
You can also read more information from a blog called “Colorado Coalition for Human Rights“.
Linked to this there is the very “strange” case of Khaled El-Masri.