DUP leader Arlene Foster has called for “calm heads” as this week’s European Council summit looms.
The pro-Brexit leader of Northern Ireland’s largest unionist party travelled to Dublin to meet Irish Taoiseach Leo Varadkar on Monday.
Mrs Foster said she was seeking a Brexit deal which worked for the UK and the Republic of Ireland.
She added: “There have to be cool heads in what is a very febrile atmosphere.”
“Great Britain is our largest market by far and we cannot have barriers,” she said.
The DUP leader said Northern Ireland sent three-and-a-half times more goods to Great Britain than to the Republic.
“So it is very important that we don’t have barriers between ourselves and the rest of Great Britain,” she added.
Mrs Foster asserted an internal barrier would not be tolerated by any other country, in reference to customs checks potentially being imposed on goods sent between Great Britain and Northern Ireland.
The DUP leader was holding her first meeting with Mr Varadkar for some period.
She said it was important to engage, that there was no point in standing back and shouting at each other, that understanding should be developed between unionists and the Irish government.
Mrs Foster added: “I very much hope we do get a deal, a sensible Brexit.
“One that works for Northern Ireland but also one that works for our friends and colleagues in the Republic of Ireland as well.”