The DUP has escalated its war of words with Taoiseach Leo Varadkar, accusing the Irish premier of "poking unionists in the eye" by talking about a united Ireland.
On Thursday Mr Varadkar said there were five ways to avoid a hard border – the reunification of Ireland; the Irish Republic re-joining the UK; the UK remaining in the single market or customs union; the border backstop mechanism; or the UK reversing the Brexit decision.
His comments have provoked anger from the DUP, with East Antrim MP Sammy Wilson saying he was "talking up support for a united Ireland to an international audience."
The DUP Brexit spokesman said: "The Irish diplomats who foolishly shoehorned such Sinn Fein rhetoric into his speech made a gross miscalculation.
"The focus and deliberate use of incendiary language designed to unsettle unionists is a telling insight to the real motives of that administration."
Speaking at a news conference with Danish Prime Minister Mette Frederiksen, Mr Varadkar said he was focused on securing an agreement on Brexit.
"I believe that's possible but in order for it to be possible all sides have to reaffirm the shared objectives - no hard border between Ireland, north and south, that the integrity of the Single Market of the European Union will be protected, and that the all-island economy will be protected," he said.
However, Mr Wilson said that the Irish government's rejection of Boris Johnson's Brexit deal "exposed their true intent with the backstop".
"It is clear from Mr Varadkar and Mr Coveney’s comments that they were committed to the backstop because it ensured Northern Ireland remained trapped in the EU," he added.
"No unionist will ever tolerate Northern Ireland’s economic future being determined by the Dublin government."
Irish foreign minister Simon Coveney, responding to criticism from DUP leader Arlene Foster, said: "I'm not getting into personalised commentary like that, the Irish Government has been consistent for three years now.
"While we respect the decision of the UK to leave the EU, we also expect the British Government would take account of Irish interests, vulnerabilities and exposure and the context of those issues of any Brexit deal that is struck."
Mrs Foster had warned Mr Coveney that he is rejecting a reasonable offer in Boris Johnson's latest Brexit paper.