Amnesty International is calling for a public inquiry into alleged Northern Ireland involvement in CIA prisoner transfer flights.
Aircraft are said to have been hired by the CIA
The human rights group says it has new evidence that planes taking prisoners to illegal imprisonment and torture landed and took off from NI airports.
The planes are said to have landed at Belfast International and City of Derry airports after January 2001.
Amnesty will publish a report on the "extraordinary rendition" on Wednesday.
The Amnesty report traces the movement of four of the CIA's 26 aircraft.
According to the report, two separate planes that have been regularly used by the CIA have passed through Belfast International and City of Derry Airports on a total of five occasions.
Shannon Airport has been used on 78 occasions and Dublin Airport on three occasions, it said.
One of the planes which has allegedly landed at both Belfast and Derry airports is the Gulfstream which is said to have made more than 100 trips to Guantanamo Bay.
It is not clear whether the aircraft were carrying prisoners when they landed at UK airports.
Amnesty International NI programme director Patrick Corrigan said: "With mounting evidence of illegal CIA rendition flights through European airspace - and multiple landings and take-offs of CIA planes at UK airports, inclduing both Belfast and Derry - there must be an independent inquiry into all aspects of UK involvement in these sinister practices.
"The Northern Ireland public requires reassurance that airports like Belfast International and City of Derry are not hosting planes used to transport prisoners for secret detention and torture.
"We are insisting that the US administration immediately ends all renditions, that all 'rendered' prisoners are identified and allowed lawyers, and that American aviation companies stop turning a blind eye to what the CIA does with their planes."
In the past, the Foreign Office has said it has no record of any requests by the US to use UK airspace or airports for rendition since the 11 September 2001 attacks on the US.
Amnesty's 41-page report, entitled Below The Radar: Secret Flights To Torture And "Disappearance", also has testimonies from people who have been detained.
"Amnesty have also talked to three individuals from Yemen who are believed to have been held at the CIA's own secret detention facilities," said the BBC's security correspondent Gordon Corera.
"The men describe being held by masked men with American accents who attempted to disguise their location. Based on details of their detention, Amnesty says it believes they were held in one of a handful of countries in Eastern Europe or Central Asia," he said.