A call by Sammy Wilson for Theresa May to "exploit the chaos in Brussels and Dublin" has been described as "despicable" by Sinn Féin MP Chris Hazzard.
The DUP's Brexit spokesman claimed cracks were emerging "in the illogical position of the EU and the Irish", enabling the Tory leader to get a better Brexit deal.
Mr Wilson said there were inconsistent messages coming from the EU about the necessity for border checks.
He also claimed a backstop that keeps Northern Ireland in the customs union and single market "as an annex of Brussels" would benefit those advocating a united Ireland.
"It is time to expose that rather than protect the Belfast Agreement, the backstop drives a coach and horses through the principle of consent and would ignore the democratic will of the NI assembly," he said.
But Mr Hazzard claimed the DUP MP was seeking "to serve the narrow agenda of the Brexiteers".
“It was Sammy Wilson and his ilk who caused this chaos by advocating and pursuing Brexit against the wishes of the people of the north," he said.
“While he may be revelling in chaos, businesses in the north across a range of sectors, community organisations and others are under intense pressure because of the uncertainty created by Brexit and many are facing an uncertain future."
Meanwhile, SDLP leader Colum Eastwood has told MPs they need to recognise that the DUP "is out of step with the majority in Northern Ireland on the backstop".
The Foyle MLA said the north would be "most adversely impacted by the decision made by majorities in England and Wales" to leave the EU.
"Despite what the DUP are saying, people here did not consent to Brexit – we need to bank the backstop in order to protect us from a hard border," he said.
"People in Northern Ireland support a legally operative backstop to protect people here."
