Sinn Fein President, Gerry Adams, is demanding the Irish government "stand-up" to the DUP and the British government over what he describes as "narrow interests" concerning Brexit.
The Sinn Fein leader issued the statement via Twitter on Tuesday afternoon.
"The Irish government needs to stand up against the narrow interests of the DUP and the English Tories and get the best deal for all people of the island of Ireland," said Mr. Adams.
"We [Sinn Fein] are certain any deal must ensure that the North remains within the Customs Union and the Single Market.
"This is the only way of ensuring stability and certainty for Irish agriculture, Irish business and Irish peoples' lives - their prospects and prosperity," added Mr. Adams.
Mr. Adams issued the statement the DUP derailed a deal between the British and Irish governments and the EU over issues concerning the Irish border post-Brexit.
SDLP leader and MLA for Foyle, Colum Eastwood, accused the DUP of putting their own agenda before the will of people living in the North of Ireland.
"For months, the SDLP has been making the case that the only way to avoid a hard border and a hard Brexit on the island of Ireland is to maintain membership of the Single Market and the Customs Union. However you want to label it, the end result must be the same," said Mr. Eastwood.
“Reports that the UK could concede the principle that there must be ‘continued regulatory alignment’ with the rules of the Single Market and the Customs Union across Ireland, particularly in areas of North/South cooperation is a positive move.
“The Brexit negotiations must be driven by the best interests of people on these islands, not by narrow isolationist ideology. All steps must be taken to protect the North’s economy, our political progress and the terms of the Good Friday Agreement. That has long been the position of the European Union. It is welcome that the British Government now seems to be accepting that position," he added.
Mr. Eastwood called on the DUP to "act in Northern Ireland's interest".
"The DUP now must move to act in Northern Ireland's interest, not simply serve the their own interests.
“The SDLP will continue to exert influence on the negotiations through our sister parties and Heads of State in the Party of European Socialists and through ongoing dialogue with the Irish Government. Our continued goal will be to protect the interests of people on this island."