The Secretary of State for Northern Ireland had floated a proposal
The Taoiseach Enda Kenny says there is no deal with Britain on the use of Irish ports of entry for UK migration checks because we do not know what they are looking for.
His comments come after the British Secretary of State for Northern Ireland, James Brokenshire, suggested it as a solution to prevent a hard border between Northern Ireland and the Republic.
Mr Brokenshire told The Guardian earlier this month he wanted to strengthen the combined UK and Ireland border.
"We are already working closely with the Irish government and other members of the common travel area to prevent people from seeking to evade UK immigration controls from entering via another part of the CTA (Common Travel Area)," he said.
"There is a high level of collaboration on a joint programme of work. This includes investment in border procedures; increased data sharing to inform immigration and border security decisions; passenger data systems enabling the collection and processing of advance passenger information; and harmonised visa processes.
"The open border for people and businesses has served us well and no one wants to see a return to the borders of the past," he added.
The Tánaiste and Justice Minister Frances Fitzgerald subsequently said the comments were not surprising as there is already co-operation on security matters.
While the Taoiseach has told the Dáil there is no such deal in place.
"We don't have agreement, because we don't low yet what the British government are actually looking for here.
"Is it a hard Brexit - exit from the customs union and the single market, and control at their own borders - or is it something else?".