Sinn Féin Leader Mary-Lou McDonald has accused the DUP of betraying the public by "pursuing a Tory-led Brexit at any cost".
Speaking at Stormont on Monday, she criticised the ‘playground rhetoric’ of the DUP after MP Sammy Wilson accused the Irish Government of ‘Brit-bashing’.
Mr Wilson accused Irish deputy premier Simon Coveney of "belligerent Brit bashing" for advocating an EU/UK customs partnership post-Brexit.
His comments came after Simon Coveney dismissed the idea of using technology as a solution to the Irish border problem post-Brexit on the BBC’s Andrew Marr programme.
He claimed it would put the Good Friday Agreement at risk and that a seamless border was the only answer.
Mrs McDonald said the DUP had been "playing games" and stalling for time and insisted a firm resolution to the border problem had to be struck ahead of June's European Council summit.
“The DUP are on the wrong side of the Brexit argument and every time they argue for it, they actually betray the best interests of everybody who lives in the north of Ireland, whether nationalist or unionist," she said.
“They have been found out and are now hiding behind that type of bluster.
“The more serious issue is the fact that almost two years on from the EU referendum, we still await any sense of a plan or an answer from the British Government in respect of the Irish question."
The Sinn Fein President says there will be no agreement until a solution to the Irish border question is found.
“This is despite the fact that it has been made very clear to Theresa May and her government that there will be no agreement until we have a solution that ensures there is no hardening of the border in Ireland. A solution that ensures there will be no disruption to commerce and industry, the provision of services and the rights of citizens in the north of Ireland," Ms McDonald said.
“But still the Tory government plays games, they propose fantastical non-starters that they claim are solutions related to technology – just for the purpose of clarity there is no technological answer to these matters.
“These are political questions, these are legal questions, these are questions that revolve around protecting people’s livelihoods and the protection of the Good Friday Agreement. Nothing less than that is acceptable.”
DUP MEP Diane Dodds said her party would not be taking direction from Sinn Fein.
“The DUP continues to work closely with the Government at Westminster to ensure that Northern Ireland’s unique circumstances are accounted for and addressed in the Brexit negotiations. We take our direction and mandate from those who elected us to office, not from the Sinn Fein leadership," Mrs Dodds said.
"By refusing to take up their seats in the House of Commons Sinn Fein representatives would rather address the empty corridors of Stormont than represent their constituents at Westminster and make their case directly. Ultimately it is this that amounts to a ‘reckless’ and ‘cavalier’ approach to the concerns of people living across Northern Ireland, including those in border communities."
"It is clear that the Irish Government and nationalist politicians in our Province wish to use a lack of progress on border solutions to press for the whole of the United Kingdom to remain in the Single Market and the Customs Union. Just as Michel Barnier’s proposal to annex Northern Ireland in customs terms was roundly rejected, these efforts will fail."