The European Union's chief Brexit negotiator has admitted the UK quitting the EU will hurt the 27 remaining member states.
Speaking in Ireland, Barnier said that some states, like the Republic, would be more dramatically affected than others, but stressed his desire to reach a deal with Britain.
Addressing a joint sitting of the Irish Parliament, he also said that the EU would work to avoid a hard border.
"Brexit will come at a cost. Also to us, the 27," Barnier said.
"I am fully aware that some member states will be more affected than others and so as chief negotiator my objective is to reach a fair deal. A deal that defends the interests of the entire EU, but also those of individual member states."
Barnier will visit a food production business close to the Irish border tomorrow, and the Brussels diplomat stressed the EU's awareness of concerns around the return of tensions with Northern Ireland.
"European integration helped remove borders that once existed on maps and in minds," he said
"Now Brexit changes the external borders of the EU, but I will work with you to avoid a hard border."
Barnier also stressed "I want us to reach a deal", but added the EU would consider Ireland's interests and the bloc's interests to be one and the same.
Irish Taoiseach Enda Kenny welcomed the supportive comments from Barnier, adding that recently agreed negotiation guidelines would provide "an excellent basis" for the talks.