The DUP has accused the Irish Government of having a 'hysterical and self-centred' response to Boris Johnson's Brexit demands.
It comes amid the continuing reaction to Mr Johnson's first House of Commons address as British prime minister.
On Thursday, Boris Johnson laid out his Brexit plan - including his insistence that the Northern Ireland backstop be abolished in any Brexit deal.
However, that demand was swiftly rejected by EU and Irish leaders.
Speaking during a visit to Belfast yesterday, Simon Coveney said Mr Johnson's speech marked a "very bad day" in Brexit negotiations.
The Tánaiste said: "[Boris Johnson] seems to have made a deliberate decision to put Britain on a collision course with the European Union and Ireland in relation to the Brexit negotiations."
Meanwhile, the Taoiseach warned Mr Johnson yesterday evening that the new British prime minister will have to row back on some of the things he has said in recent days if he truly wants to secure a Brexit deal.
DUP MP Sammy Wilson today claimed the Irish Government had 'overplayed their hand'.
He said: “The hysterical and self-centred response from the Irish Government to the reasonable demands of the Prime Minister to have the backstop removed from any exit deal from the European Union speaks volumes.
"The megaphone reaction demonstrates that the blatant attempts by Leo Varadkar and co to use the Irish border as a means of undermining Britain’s referendum has [backfired] on them and they know it. "
He added: "The Irish Government walked the world stage and styled themselves as the victims of British aggression.
"‘Poor little Ireland’ may have worked in the past but people are growing tired of the same old tune. The game is up."
'Aggressive language'
In comments quoted by the Belfast Telegraph, DUP MP Ian Paisley Jr has accused Minister Coveney of using "unhelpful and unnecessarily aggressive language".
Mr Paisley said: “It is high time Simon Coveney showed some respect for the constitutional situation.
"If he wants to make inflammatory statements, he should do so in his own country and be fully aware of the damage he is doing.”
He suggested the Irish government is entitled to speak its mind, but to do it in Stormont is 'provocative and disrespectful'.
Meanwhile, Boris Johnson today reiterated his belief that the backstop has to go.
Speaking in Manchester, he said: "If we get rid of the backstop, whole and entire, then we're making a lot of progress."
Asked whether European leaders were warming to him, he suggested he had "friendly relations" with many EU foreign ministers and leaders already.
He insisted: "The approach of the UK government is not going to be disengaged or aloof or waiting for them to come to us.
"We are going to try and solve this problem, but of course we're going to do it in a spirit of friendship and cooperation... but we can't do it as long as that anti-democratic backstop - that seeks to divide our country - remains in place."
