He has met Minister Simon Coveney for Brexit talks in Brussels
The European Union's chief Brexit negotiator says the bloc has "strong solidarity" with Ireland.
Michel Barnier was commenting after he held talks with Foreign Affairs Minister Simon Coveney in Brussels.
He tweeted: "Another good meeting w/ @simoncoveney. I updated on #Brexit state of play. Strong solidarity with #Ireland: Irish issues are EU issues."
Minister Coveney also thanked Mr Barnier for "reaffirming EU solidarity with Ireland" on the issue of Brexit.
Mr Coveney also has Special Responsibility for Brexit.
It comes as British Prime Minister Theresa May heads to Brussels for more talks aimed at breaking the deadlock over the UK's Brexit negotiations.
She is meeting European Council president Donald Tusk and is expected to increase the UK's Brexit "divorce bill" offer.
But her offer - which could rise from around stg£20bn to up to stg£40bn (€22.3bn to €44.7bn) - is conditional on the EU agreeing to begin talks on post-Brexit trade.
Mrs May is in Brussels for an Eastern Partnership summit, where leaders will discuss moves to protect former Soviet bloc countries from the new threat posed by Russia.
During the summit, she also hopes to hold one-to-one meetings on Brexit with other key European leaders.
She is set to focus on issues around the Irish border and concerns over a 'hard Brexit' on Gibraltar.
Last week, Mr Tusk told Mrs May the EU needed greater clarity on the terms of Britain's withdrawal - including the financial settlement - by early December.
He said only then would EU leaders give the go-ahead for phase two of Brexit negotiations to start at their next summit on December 14th and 15th.
While Taoiseach Leo Varadkar has asked a written guarantee that there will be no return to a hard border on the island of Ireland.
Speaking last week, Mr Varadkar said: "We've been talking 18 months, we've been given assurances now for 18 months since the referendum that there'll be no hard border in Ireland, that there won't be any physical infrastructure, that we won't go back to the borders of the past.
"We want that written down in practical terms in the conclusions of phase one."
He denied that Ireland was pushing for Northern Ireland to remain in the EU Customs Union while the rest of the UK remained outside.
"It's not saying that, and I don't think it is hugely divergent from the UK position that they would like to enter a customs partnership with the EU after Brexit.
"What we want to do is set the parameters for the talks about trade."
Speaking ahead of Mrs May's talks with Mr Tusk, her spokesman played down suggestions that it was a meeting exclusively to discuss the "divorce bill".
"There are a number of issues which I'm sure they will want to discuss - the financial settlement, that will be one of them, also of course Northern Ireland and citizens' rights," he said.
Additional reporting: IRN