PARIS (AP) — The European Union's chief Brexit negotiator, Michel Barnier, says disagreement over the Ireland border issue could lead to the discussions with Britain failing.

Speaking on France Inter radio Friday, Barnier said a deal on the border issue is a "prerequisite" for a successful outcome to the divorce talks.

Barnier says avoiding a border between EU member Ireland and Northern Ireland, which is part of the United Kingdom is a "condition for peace and stability for this island following many tragedies."

The Irish border will be U.K's only land frontier with the EU after Brexit.

Asked whether the issue could lead to Brexit talks breaking down, Barnier said: "the answer is yes."

Both sides have said they want to avoid a hard border.