DUP leader Arlene Foster welcomed Prime Minister Theresa May's speech in Florence on the UK's exit from the European Union describing it as a "positive vision", while Sinn Fein president Gerry Adams dismissed it as the "same old story".
The Prime Minister emphasised protecting the Belfast Agreement and the Common Travel Area between the Republic and Northern Ireland as well as repeating there would be no customs checkpoints along the border.
Mrs May also said she wanted the UK to be the EU's "strongest friend and partner" saying there should be a two-year transition period after Brexit.
DUP leader Arlene Foster welcomed the speech describing it as a "positive vision".
She said: "A strong signal has been sent in her speech, that although we are leaving the EU we still want to have very positive relationships with our nearest neighbours. This is particularly important to Northern Ireland.
"The reassurances to EU citizens in the United Kingdom will be warmly welcomed, as will the proposed new economic partnership.
"Certainty is paramount. We welcome the clarity that after the United Kingdom leaves the EU we will not be members of the Custom Union nor the EU Single Market. Any transition period should be for the absolute minimum period.
We voted to join the EEC as a nation and we must also leave the European Union as a nation. Arlene Foster
"The wishes expressed in the referendum should be delivered without undue delay. Whilst genuine need for proper planning and adjustment should be accommodated, any future payments to EU budget should also be minimised."
Mrs Foster continued: "We understand that the PM has an important task in ensuring that Her Majesty's Government presents a united front in the face of aggressive EU negotiators who seem determined to do as much damage as they can to the UK. We are keen to see the negotiations move quickly to the next stage to allow the crucial issue of trade to be dealt with and our future relationship with the EU.
It was nothing but the same old story. Gerry Adams
"In terms of Northern Ireland, there’s nothing that’s going to separate us politically from the rest of the United Kingdom such as a border in the Irish Sea. We delivered this message to Guy Verhofstadt earlier this week. We voted to join the EEC as a nation and we must also leave the European Union as a nation.
"All in all, I am pleased that the Prime Minister has decided to innovate and build a new relationship rather than imitate the agreements already in place between the EU and other partners.”
Taoiseach Leo Varadkar gave the speech a cautious welcome. He said it was not a game changer, but did welcome the announcement of a transition period.
The UUP said it was a time for the Republic to build a stronger relationship with the UK. Alliance described it as a missed opportunity for the UK to adopt "a more realistic approach".
Sinn Fein said the speech "failed to impress" and reiterated its call for special status for Northern Ireland.
"It was nothing but the same old story," said Gerry Adams.
"There was no hard proposal or detail. On the issue of EU citizen’s rights, which include all those living in the North, the British PM reiterated her total opposition to any real role for the European Court of Justice. And she did not deal in any meaningful way with the issue of the settlement Bill.
“In defence of the economies of this island, the government should insist on special designated status for the North as a way of keeping the island of Ireland within the Single Market and Customs Union.
“It should also insist, as one way of defending the integrity of the Good Friday Agreement, that the Good Friday Agreement will be included as a Protocol in the withdrawal treaty. This would provide legal protection for the Agreement following Brexit.”