The CIA flew 1,245 secret flights into European airspace, according to a European Parliament draft report obtained by ABC News.
The report is the result of a year-long investigation into secret CIA "extraordinary rendition" flights and prisons in Europe.
No European country has officially acknowledged being part of the program.
But citing records from an informal meeting of European and NATO foreign ministers last December that included Secretary of State Condoleezza Rice, the Parliament's draft report concludes "member states had knowledge of the programme of extraordinary rendition and secret prisons."
The report said the recently fired head of Italian intelligence, General Nicolo Pollari, "concealed the truth" when he appeared before the Parliament's investigating committee and stated "that Italian agents played no part in any CIA kidnapping."
The report detailed the involvement of many European countries in what it called the CIA's "illegal" program.
It listed the number of CIA flights, or stopovers, it found in a number of countries.
Italy: 46 stopovers.
United Kingdom: 170 stopovers.
Germany: 336 stopovers.
Spain: 68 stopovers.
Portugal: 91 stopovers.
Ireland: 147 stopovers.
Greece: 64 stopovers
Cyprus: 57 stopovers.
Romania: 21 stopovers.
Poland: 11 stopovers.