Brexit could lead to an increase in smuggling along the border in Ireland, according to former Irish taoiseach John Bruton.
Both he and another former Irish leader, Bertie Ahern, were giving evidence on the implications of Brexit for Ireland to the Lords’ EU Committee.
Both men agreed with the views of senior EU diplomats that the open border arrangement could continue after the UK leaves the European Union, and that the need to impose passport checks would be unlikely, but that would pose a risk to the movement of goods that should be subjected to tariffs between the two countries.
In response to a direct question by the committee on whether Brexit could be abused and become a smugglers' charter, Mr Bruton said: "Yes is the answer to that question too."
It has been suggested that Irish ports and airports could become entry point into the UK by proxy, and as serve as a frontier for British immigration, but that dismissed out of hand by Mr Ahern.
"I quite frankly just found that unbelievable," he said.
"To put that suggestion forward is a total lack of understanding of how people think, north and south, of either tradition. It just would not happen."
The idea was floated in recent weeks with Northern Ireland Secretary James Brokenshire saying that governments in London and Dublin would work to strengthen the Republic's external borders after Brexit.
The opinions of the former taoisigh were sought as part of the parliamentary committee's inquiry into the impact of Brexit on UK-Irish relations, the peace process, the return of a hard border and how the common travel area between Britain and Ireland could be affected.
Mr Ahern urged the Irish government to appoint a dedicated minister to deal with Brexit.
