The Minister for Finance has said it is not possible to have formal, bilateral agreements between Ireland and Britain.
Michael Noonan was reacting to a report published by the House of Lords EU Committee which has called Brexit a huge challenge for Ireland, and appealed for the forthcoming UK-EU negotiations to recognise the special nature of UK-Irish relations.
The report calls on the UK and Irish governments to negotiate a draft bilateral agreement which could then be agreed by the EU as part of final negotiations on the UK leaving the EU.
While Mr Noonan welcomed the report, he said formal negotiations will take between Britain and the European Union.
The report started with the potential challenges for UK-Ireland relations, as well as looking at the issues it raises for Northern Ireland.
The report recommends power over freedom of movement to EU nationals within Northern Ireland be devolved to Stormont post-Brexit.
They say this is one element which could be contained in a draft bilateral treaty between the UK and Ireland.
It says that treaty should also maintain the Common Travel Area and the right of free movement within the area for UK and Irish citizens.
The Committee concluded that any need for customs checks which might arise post Brexit would make the current open land border in Northern Ireland impossible to retain.
It says that the special circumstances of Ireland - North and South - means a special solution to any problems should be sought.