EU:EU justice commissioner Franco Frattini has said he would welcome an Irish application to join the Schengen area to enable passport-free travel for its citizens.
On the eve of the dismantling of internal borders for nine new EU states, Mr Frattini said he believed such a move would be positive for the country.
But he acknowledged there were sensitivities over the issue in the Republic, and praised the Government for signing up to a range of recent initiatives to boost police co-operation across Europe. "My personal opinion is that joining Schengen would be positive for Ireland," he said.
"Of course I would prefer it, but regardless of a formal decision taken shortly, Ireland would in any case be an important part of our European club," he said.
Ireland and Britain are not involved in the passport-free zone, but they have signed up to agreements on security. Britain refuses to join the "Schengen zone" because it wants to retain control of its own borders.
The Government has cited the maintenance of the common travel area between Britain and Ireland, and principally Northern Ireland, as the only reason that it has so far chosen to stay out of the common EU border system.
However, Britain has announced plans to set up a new e-borders system that would force Irish and possibly travellers from Northern Ireland to provide passport details when they travel to England, Scotland and Wales.
This has prompted serious questions about the viability of the common travel area and caused some politicians, notably Fine Gael MEP Gay Mitchell, to prompt the Government to consider an "all-island" application to the "Schengen zone".
"If there are border controls introduced between Ireland and Britain, then I think it is time for us to join Schengen," said Mr Mitchell, who added Northern Ireland could also join the zone but remain in Britain.
The Government has so far downplayed any prospect of joining.
At an EU summit last week, Taoiseach Bertie Ahern said: "I don't think there is any discussion on it. It is not an idea that is being floated . . . I don't think it is going to happen."
Mr Ahern has told Minister for Justice Britain Lenihan to present a plan for Ireland to set up its own e-borders system.