The flights involved three private planes, but the report gives no specific dates for the stopovers or the origins and destinations of the flights. Rather, the flights are listed by identification numbers and are shown to have been registered to what the organization says are well-known CIA front companies.

The Czech Airport Authority independently confirmed for The Prague Post that the three planes in question stopped at Ruzyně for an average of 90 minutes to refuel, but said its records listed only 15 stopovers, not 20. Airport officials did not release dates attached to the flight data.

"We ask the government to see if the Czech Republic actually participates in CIA flights," said Zdeněk Rudolský, director of AI's Czech branch. "We want to find out if the United States got diplomatic assurances, if Czech authorities knew in advance of these flights."

The 43-page report is by far the most extensive AI has compiled recording the CIA's rendition activity transporting terrorism suspects and prisoners of war to detention facilities without a legal process.

AI contends that these prisoners end up being tortured or simply disappear, and wants to end the practice.

Pressed further about prisoners on flights using Ruzyně, Rudolský said, "I think we can only say we do not know if there were detainees on these flights."

Several ministries and Prime Minister Jiří Paroubek's office deferred questions to the airport authority. Jan Šubrt, a spokesman for the country's intelligence agency, the BIS, said, "We are not monitoring airport traffic. That's completely beyond our activities."

The airport authority said only that it did not know the nature of the flights in question.

Under the International Civil Aviation Agreement of 1944, private planes can fly over or make technical stops in countries without giving proper notice to authorities.

The AI report lists close to 40 countries worldwide where rendition flights stopped, many in Europe.

The three planes that stopped in Prague also stopped 154 times in Frankfurt, Germany, the report says.