The Government has instructed senior officials to prepare a plan to deal with the ending of the Common Travel Area between Ireland and Britain, which has existed since the foundation of the State in 1922, writes Stephen Collins, Political Editor.
The move follows communication between the British and Irish authorities about the development of an electronic border control system by Britain by 2009.
It means that people travelling by air or sea between the two countries will be required to carry passports, so that information about their travel plans and movements will be available to the authorities in both states.
The British have decided to develop a so called e-border system in order to track the movements of terrorist suspects, criminals and illegal immigrants.
In response to the British decision to press ahead with the implementation of the system at the earliest possible date, the Government is preparing to establish a similar system. Officials have been instructed by the Cabinet to prepare a memorandum on the formation of an Irish Border Information System and to detail how it will work with its British counterpart.
It is expected that the Irish system would be broadly similar to the British one.
Passenger information will be collected by carriers and sent to an Irish border operations centre, where it will be screened against immigration, Garda and other watch-lists.
At its weekly meeting yesterday the Cabinet was informed of the British determination to press ahead with its e-border system and Ministers were told of the potential impact of the system on travel by Irish citizens to Britain and on the operation of the Common Travel Area.
Ministers were also informed of plans, already well advanced, for the development of an Irish Border Information System. The issues will be the subject of a detailed memorandum to Government in the near future.
The British e-border system is designed to operate by electronically collecting and analysing passenger information in advance of travel to or from the country. This procedure will result in an "alert" if the person travelling is on a watch-list.
Free movement of people between Ireland and Britain has existed for hundreds of years and the Common Travel Area survived Irish independence in 1922 and the declaration of a Republic in 1949. Throughout the period since independence, even during the second World War and the IRA terrorist campaign, travel has been possible without any identity document between the two states.
The British e-border system will automatically require all air and sea passengers to be in possession of a valid passport to facilitate a journey within the Common Travel Area.
While Ryanair has required air passengers between the two countries to carry photo ID since September 11th, 2001, it is still perfectly legal to travel between the two countries without a passport.
It does not appear that the British intend to apply the e-border to the land border between the Republic and the North, as that would be impossible to police.
However, the application of e-border controls in both countries with close co-operation between the respective authorities would effectively seal off the two islands.
In July the British prime minister, Gordon Brown, said the cabinet secretary had been asked to report by this month on how the e-border could be implemented "very soon".
Mr Brown said the electronic screening of all passengers checking in and out of the United Kingdom was a priority. Having a system of e-borders in place by 2009 and the introduction of biometric visas by March of next year were crucial parts of that plan.