Returning to a hard border would be like “rebuilding the Berlin Wall,” Mary Lou McDonald has claimed.
The Sinn Féin leader believes it would be a disaster for the country in “many ways” and that everybody must work to avoid the terrible prospect during Brexit.
Ms McDonald was speaking to political reporters after talking to British Prime Minister Theresa May on the phone at lunchtime today.
She said that the British PM agrees with her that there can be no return of a hard border on the island of Ireland no matter what.

However, Ms May was not able to give any ideas or suggestions on how we could avoid a border if we have to have customs checks after Brexit.
The EU has said that there will have to be checks if the British don’t agree to regulatory alignment or if there is a crash Brexit.
Ms McDonald said: “I think it’s important that we understand that this isn’t just about the economy and it’s not just about trade.
“This is not a technical dilemma, this is a political question.
“And the idea of reinstating in any form the border on the island of Ireland is almost like suggesting we rebuild the Berlin Wall, from a political point of view.
“We have to be very, very clear that we all protect political progress and we’ve set all of that out for the diplomats and Ms May this morning - I have to say not for the first time.”

Fifth of British public would prefer Northern Ireland leave UK and join Republic
The Sinn Féin chief said that she reminded Ms May again that a United Ireland was the best solution going forward.
She added: “We’ve also alerted all of them again to the fact that there is actually a solution, the only solution that fully answers the priority of the Good Friday Agreement and the needs of Ireland and the protection of the Single Market, and that option is the holding of a border poll and the removal of the border.”
UK MPs reject every option for a way forward in indicative votes on Brexit