A courtroom battle in New York between two private aviation companies who were contracted to carry out rendition flights by the US government has shed light on the secret airlift of suspected terrorists by CIA operatives using airports across Europe and Asia, including Shannon.

Court files show that the two parties to the lawsuit, Richmor Aviation and SportsFlight Air, which acted for US government contractor DynCorp, are in dispute over unpaid costs from rendition flights.

Richmor operated a Gulfstream jet, which is recorded landing on several occasions at Shannon between 2001 and 2005 and which was involved in the rendition of the Egyptian cleric Abu Omar.

The aircraft is suspected of having refuelled at Shannon before transporting al-Qaida member Abd al-Nashiri — the prime suspect for the bombing of a US navy ship in Yemen in 2000. The files reveal that the flight, which involved stops in Dubai, Afghanistan, London and Washington, cost $198,000 (€138,000).

Anti-war group Shannonwatch, which claims it has evidence of 20 suspected rendition flights using Shannon over an eight-year period, said such costs included profits made by Shannon Airport.

“The airport facilities were used repeatedly over the years by private companies engaged in illegal and immoral activities,” said a group spokesperson.

“Irish politicians now have to be made accountable for their failure to ensure that Ireland was not complicit in rendition, kidnap and torture.”

Amnesty International Ireland said the weakness in procedures and legislation that allowed the CIA to use Shannon for rendition flights had never been fixed.

“The Government has an opportunity to break with the failure of the previous administration to protect Irish airspace and human rights,” said the organisation’s executive director, Colm O’Gorman.

He also called on the Oireachtas Committee on Investigations, Oversight and Petitions to investigate.

The US embassy in Dublin did not respond to a request for comment.

A spokesman for the Department of Foreign Affairs said the Programme for Government pledges to prohibit the use of Irish airspace, airports or aircraft for purposes “not in line with the dictates of international law”.

He referred to a speech by Foreign Minister Eamon Gilmore in the Dáil in March, in which he said: “Shannon will not be used as a means of rendition, facilitating torture or any other activity which violates human rights.”

Secret diplomatic cables released by WikiLeaks last year revealed that former US ambassador James C Kenny noted in 2006 that the Government had “acted to ensure continued US military transits at Shannon in the face of public criticism” despite public concern that the airport was being used for extraordinary rendition flights.

Other cables highlighted how former foreign affairs minister Dermot Ahern told another US ambassador, Thomas C Foley, he was convinced that three flights had refuelled at Shannon.

The Government claimed that it had relied on reassurances by the US that it had not operated such flights through Irish airports or airspace.