BELFAST (Reuters) – The small Northern Irish party supporting the British government insisted on Friday that no barriers to trade be erected between it and mainland Britain in any Brexit deal and that the United Kingdom must leave the European Union as one.

Reminding Prime Minister Boris Johnson that it was “very relevant” to the parliamentary arithmetic in London, Democratic Unionist Party (DUP) leader Arlene Foster added that any deal that aligns the British-run region to parts of the EU’s single market must have democratic consent within Northern Ireland.

“The DUP has always indicated that the United Kingdom must leave the EU as one nation and in so doing that no barriers to trade are erected within the UK,” she said in a statement. “In December 2017 we insisted that democratic consent was required in circumstances where Northern Ireland would align alongside specific sectors of the EU single market.

“We have held steadfast to that position whilst recognizing the need to be flexible and look at Northern Ireland specific solutions achieved with the support and consent of the representatives of the people of Northern Ireland.”

She went on: “In order to secure a sensible deal for everyone, it is important that the European Union understand that to maximize the prospects of agreement there will need to be a clear acceptance that the economic and constitutional integrity of the whole of the United Kingdom will have to be respected as we leave.” 

Reporting by Amanda Ferguson, writing by Padraic Halpin; editing by Stephen Addison