The State must inspect any US flights landing at Shannon suspected to be carrying prisoners in order to ensure these passengers are not being sent on for torture, the Irish Human Rights Commission will declare today.
The commission's statement on so-called "extraordinary renditions" by the US authorities has been in preparation for over a month.
In it, the commission will urge the Government to seek the US government's agreement "as a matter of urgency" to inspections of aircraft suspected of involvement in the practice.
The State is obliged under domestic and international law to ensure that prisoners are not taken on to countries where they could be subject to torture or other forms of degrading treatment.
During talks in Washington in early December with the Minister for Foreign Affairs, Dermot Ahern, US secretary of state Condoleezza Rice insisted that prisoners were not being transported through Shannon.
However, the commission is believed to have come to the conclusion that the State cannot merely accept the US's guarantees if it is to comply with its international obligations to prevent torture.
Members of the commission are believed to have carefully studied the State's duty under the Human Rights Commission Act, the United Nations' Convention Against Torture and the European Convention on Human Rights.
Though the commission refused to comment last night in advance of today's publication, The Irish Times understands that it believes the State must formally investigate the charges that have already been made about Shannon.
The involvement of the human rights body will increase the pressure on the Government, which has quietly emphasised the diplomatic difficulties that would surround carrying out such checks on aircraft.
The Bush administration has become increasingly irritated by the European Union's focus on the issue, particularly following allegations that it ran two unofficial prisons in Poland which are now being investigated. The Council of Europe has warned member states that they have "a positive obligation" to ensure that they do not breach the 50-year-old European Convention on Human Rights.
Article 3 of the convention, which does not allow for any exceptions to be made, makes it clear that "no one shall be subjected to torture or to inhuman or degrading treatment or punishment".
By this measure, the State would not be able to claim ignorance as a defence if it ever emerges that prisoners have been taken on the Shannon flights, since the convention also covers a country's airspace.
Six aircraft chartered by the US Central Intelligence Agency have landed at Shannon 43 times over the last four years, according to figures released by Minister for Transport Martin Cullen.
However, Amnesty International believes that the CIA has landed more than 50 times in less than three years and flown more than 800 flights around, and from western Europe ferrying prisoners.
One of the aircraft seen frequently at Shannon, a Gulfstream V, which has had its call sign changed three times, is known as "the Guantanamo Bay Express" because it has made more than 50 trips to the Caribbean detention centre.
Up to now, the State has said that credible allegations would be investigated by the Garda, but, so far, no such investigation has begun - despite the circumstantial evidence provided by Amnesty, Human Rights Watch and others.
The Human Rights Commission Act, 2000, which was set up as part of the Belfast Agreement, gives significant powers to the commission, which is headed by former Fine Gael TD and senator, Maurice Manning. Section 8 of the Act states that one of the functions of the commission is "to keep under review the adequacy and effectiveness of law and practice in the State relating to the protection of human rights".
Furthermore, the commission is also empowered to make recommendations to the Government for ways "to strengthen, protect and uphold human rights in the State".