The president of Sinn Fein has slammed Boris Johnson's Brexit plan, calling it "profoundly stupid".
Mary Lou McDonald said Ireland faced “its greatest threat and challenge in a generation” at the hands of the UK government.
“Boris Johnson follows a fantasy in which the rights and interests of the Irish people can be cast aside,” she said.
“Mr Johnson's stupid, dangerous fantasy cannot become Ireland's nightmare, because Brexit is a very English problem and the consequences of it cannot be shifted on to Ireland.”
On Monday, Mr Johnson said he had an “abundance of proposals” that could serve as an alternative to the Irish backstop, but is yet to reveal these plans.
The European Union has insisted any Brexit deal must feature the backstop; however Mr Johnson has called it “anti-democratic”.
Ms McDonald said she believed the Prime Minister’s proposals would lead to a hard border dividing Ireland.
“The Irish people will not allow our country, our communities, our economy or our peace to be vandalised by him,” she said.
“There can be no return to a hard border, customs checks, and no more division on this island to suit the needs of a British government that has no interest in Ireland's future.”
DUP leader Arlene Foster met with Mr Johnson in Downing Street on Tuesday and said she continued to work with the Prime Minister to find a deal.
She said a backstop that only applied to Northern Ireland would mean one part of the United Kingdom would essentially be left in the European Union.
However Ms McDonald said it was "not perfect", but that “no viable alternative exists to the backstop”.
“It's the least-worst option and broad Irish opinion supports that,” she added.