Former taoiseach Bertie Ahern will tell a parliamentary committee on Thursday that if Britain leaves the customs union some form of Border set-up will be inevitable.
Mr Ahern will say the status of the State as an EU border frontier will present a challenge in terms of keeping access as open as possible between Northern Ireland and the Republic, as well as the islands of Ireland and Britain.
He is due to address the select committee on Brexit in Leinster House on Thursday. It his his first appearance in the Oireachtas since he gave evidence during the banking inquiry in 2015.
Mr Ahern cited a recent conversation he had with Pascal Lamy, the former EU commissioner for trade and director general of the World Trade Organisation, about what eventualities might emerge.
“[Mr Lamy] said clearly that if the EU border with the UK happens to be our border, then you will have to have a customs control.
“There is nobody more experienced than Pascal Lamy and it is no good listening to people who don’t know what they are talking about,” he said.
Two options
Mr Ahern said there were “two ways” to overcome that.
He said the British might try to find their way into the customs union, something the EU has insisted could not be done without abiding by its four principles, including guaranteeing the free movement of people.
Mr Ahern raised the possibility that the British government “could try and negotiate around that”.
The second option canvassed by Mr Ahern was that the Border would be placed not between the Republic and Northern Ireland but between Northern Ireland and Britain.
He said they were the only two possibilities and anything else was “wasted talk”.
The former Fianna Fáil leader is also expected to outline to the committee the implications for Ireland, some of which he believes will be positive.
