Alliance Brexit spokesperson Stephen Farry MLA has said the Prime Minister's escalation of language around Brexit negotiations is a potentially "grave and historic mistake".
Dr Farry was speaking after Theresa May said talks had reached an impasse, with the rejection of her Chequers Plan by the EU as "not acceptable".
"The Prime Minister has placed the UK in a massive hole and rather than stop digging she has ordered a JCB," he said.
"There is little point in lashing out at the EU. It is the UK leaving the EU, not the other way around. The Chequers Plan was developed in a bubble, and there have been plenty of warnings from the EU it wouldn't work.
"The plan doesn't respect the fundamental choices facing the UK - the only options to avoid a hard border in Ireland after Brexit are either the UK remaining in a Customs Union and the Single Market or the provision of special arrangements for Northern Ireland,
"Time is rapidly running out to conclude a withdrawal agreement and transition deal. This requires prompt agreement on the backstop for Northern Ireland. This is not a political and constitutional crisis but a pragmatic and economic intervention.
"In dramatically escalating the rhetoric, the Prime Minister and her DUP allies are backing the UK into a corner, and making a potentially grave and historic mistake."