Speaking in Dundalk during a two-day visit to Ireland and Northern Ireland, EU chief Brexit negotiator Michel Barnier has urged rapid agreement by June on the scope of any British alignment with the single market. Video: DFA

Ireland will be used as a key pressure point at a crucial summit next month to force the UK to clarify its future relationship with the EU, Michel Barnier has said.

In a private briefing in Brussels last week, the European Union’s chief negotiator also insisted Brexit does not threaten the constitutional status of Northern Ireland and asked for “drama” to be taken out of the Border proposals.

In a briefing to representatives of the EU27, the bloc’s remaining member states, he said the risk of a breakdown in the talks later in the year will be heightened if there is no “early progress on Irish issues”. He was reporting on his recent trip to Northern Ireland and Ireland. An account of his briefing was sent to Dublin by Irish officials.

The EU has proposed this would mean Northern Ireland remaining in the customs union after Brexit. That has been rejected by the British prime minister, Theresa May, and the DUP, which supports her Conservative government in a confidence-and-supply deal at Westminster.

“France also shared Barnier’s view on the need to reach agreement on outstanding withdrawal-agreement issues, including Ireland, by June,” the notes say. “Germany said it was essential that the Irish issue was not left ‘open to the end and then isolated’.”

‘Specific leverage points’ Mr Barnier said the EU “had specific leverage points” at European Council summits last December and March. “In June, the primary leverage point will be to make clear to the UK that finalising the outstanding aspects of the Withdrawal Agreement, ‘including on Ireland’, is a precondition to a constructive discussion on the future,” the account of his briefing said.

Mr Barnier said the backstop does not affect the constitutional status of Northern Ireland but only sets out what checks are necessary after Brexit. He argued there are already checks between Britain and Northern Ireland for agricultural produce. “What he has learnt from his visit to Ireland/Northern Ireland is that all sides need to take the drama out of what is being proposed. Barnier repeatedly said he was moved by all communities in Ireland.”

Speaking yesterday, the DUP leader, Arlene Foster, said Northern Ireland must “move in lockstep” with the rest of the United Kingdom. “We don’t believe we have to stay in the customs union to have free flow between ourselves and the Republic of Ireland.”