He is giving an update on border negotiations and meeting business groups
The chief Brexit negotiator with the European Union says he is not playing tactics with the vital interests of Ireland.
Michel Barnier was speaking at the the All Island Civic Dialogue in Dundalk.
The backstop deal to avoid a hard border has been the main talking point.
Michel Barnier said where Ireland goes, the EU goes.
"The consequences of Brexit should not, and must not, lead to the return of a hard border: neither on maps or in minds".
After DUP leader Arlene Foster claimed he was out of touch with unionism, Mr Barnier said he has never been aggressive in negotiations.
"I have been never aggressive (from the) very beginning, day one of this negotiation, never.
"There is no spirit of revenge, no spirit of punishment.
"Let me repeat that I profoundly regret the Brexit, for many reasons - and I have been never aggressive".
Mr Barnier is on a two-day visit to Ireland, attending the All-Island Civic Dialogue on Brexit in Dundalk on Monday.
He has also given an overview of the ongoing Article 50 negotiations with the UK at the Dundalk Institute of Technology.
Mr Barnier is meeting Taoiseach Leo Varadkar and Tánaiste Simon Coveney.
He is also meeting participants from the 'Young People and Brexit' session, as well as the Chief Commissioner of the Irish Human Rights and Equality Commission and the Chief Commissioner of the Northern Ireland Human Rights Commission.
Following the all-island civic dialogue, he will travel to Newry in Northern Ireland - where he will have a roundtable discussion at InterTradeIreland with a number of business stakeholders and cross-border groups.
On Tuesday, he will be in Derry where he will again meet a range of business stakeholders and cross-border groups and companies.
He will finish his trip with a visit to rural representatives in Dungannon.
The visit comes as Tánaiste Simon Coveney has insisted 'substantial progress' has to be made on the Irish border issue before the next major Brexit deadline in June.
EU leaders will meet in June, and that summit is seen as one of the key deadlines ahead of Britain leaving the EU next year.
There is an ultimate deadline of October for the overall withdrawal treaty to be agreed, so it can become law before the full withdrawal in March 2019.
Additional reporting: Sean Defoe