It has been confirmed that Aldergrove Airport in Belfast and City of Derry Airport are among the UK facilities used by US planes suspected of being involved in the transportation of prisoners for torture.
Campaigners have identified six CIA planes that used UK airports for so-called "extraordinary rendition" flights. They say many of the planes were flying under cover as commercial airlines.
UK Transport Secretary Alistair Darling said today that six identified planes used the airports on 73 occasions since 2001.
There have been claims that Aldergrove had been used but City of Derry Airport had not previously been mentioned as a location for renditions.
Four of the planes — N2189M, N8183J, N368CE and N85VM — were involved in 64 non-commercial flights, which do not require permits, said Mr Darling. There was no information available on the passengers on board these planes, he added.
Flight plans for these journeys were confidentially released in January by European air navigation organisation Eurocontrol to the Council of Europe, to assist in its inquiry into allegations over secret prisons and rendition flights.
These flights went through Belfast Aldergrove and Derry Airport; Prestwick, Edinburgh, Glasgow, Inverness and Leuchars in Scotland; Stansted and Luton near London; Birmingham and Farnborough in England.
Specific details were not revealed but some of these flights came from or went to the US, Canada Fankfurt, Prague, Athens, Nice, Geneva, Genoa and Iraklion in Crete. Some of theses also involving airports in the Middle East, and one flight by N85VM from the Afghan capital Kabul which landed in Edinburgh on November 25th 2002.
Mr Darling said his department had no evidence that any of the flights were involved in rendition.
Foreign Secretary Jack Straw told MPs earlier this year that London was aware of only two cases in which the US requested and was granted permission to transfer detainees via the UK, both in 1998.
Campaigners have identified a number of aircraft which they claim are used by the CIA to transport terror suspects to the Guantanamo Bay detention centre in Cuba or to secret prisons in eastern Europe and the Middle East where they may be tortured.
The US has insisted that the rendition of prisoners is not unlawful, and that no-one aboard such flights has been tortured
Britain's National Air Traffic Service has previously said there were 200 flights through British its in the past five years by the CIA planes identified by campaigners.