Prime Minister Theresa May has responded to the letter from Northern Ireland's First and Deputy First ministers in which they sought assurances over the impact of Brexit.
In August the DUP were accused of performing a U-turn over its stance on Brexit after Arlene Foster and Martin McGuinness sent a joint letter to the Prime Minister warning that there could be serious consequences for Northern Ireland by leaving the EU.
Political rivals levelled the accusation against the pro-Brexit DUP leader after the publication of the letter to the Prime Minister, in which she and Mr McGuinness, a Remain advocate, highlighted a series of risks to Northern Ireland.
However, Mrs Foster denied the suggestion that she had a change of heart.
On Tuesday Theresa May's letter in response was revealed.
She said: "I am committed to full engagement with the Northern Ireland Executive on the UK's exit from the EU and will take full account of the specific interests of the people of Northern Ireland in order to get the best possible deal for all parts of our United Kingdom as we leave the EU."
Mrs May highlighted five areas including the treatment of the agri-food sector, the border and the energy market.
Addressing the future of the border Mrs Mary said it was "an important priority for the UK as a whole".
She said: "The UK Government, the Northern Ireland Executive and the Irish Government have all been clear that we wish to see the continuance of the free movement of people and goods across the island of Ireland and the maintenance of the Common Travel Area across the whole of the UK and Ireland, which has served us well."
Meanwhile the SDLP have hit out at why the Prime Minister's response was not announced in the Assembly chamber on Monday.
It was instead revealed on the BBC Stephen Nolan show on Tuesday.
SDLP party leader Colum Eastwood said: "It definitely isn't good enough to send a letter in August to the British Prime Minister and patiently wait for a reply. I don't even think we've got one yet.
"We should be kicking the door in of the British Prime Minister to ensure the interests of the people of Northern Ireland are protected."
The revelation came after DUP MP Gavin Robinson was discussing the Executive's "commitment" to working hard on Brexit.
To which SDLP MLA for south Down Sinead Bradley asked: "Gavin, perhaps you could ask for a reply to the letter?"
To which Mr Robinson responded: "Oh we've got a reply to the letter Sinead."
Speaking on Tuesday afternoon First Minister Arlene Foster said the letter was put in the Stormont library at the same time it was released to the media.
She said: "It was put into the (Stormont) library at the same time it was released to the media. We're challenged about being open and transparent so we have released it and we placed it in library the day after we received the letter.
"Of course this is going to be an ongoing issue and we're going to be receiving many, many letters between ourselves and the UK government and we do of course want to release those letters.
"We were going to publish the letter today but it was placed in the library and I don't see that there is any story in this at all apart from the fact that it is a significant letter from the Prime Minister in so far as she's acknowledged the five issues that we feel we needed to raise with her and she has responded in a positive way in the contents of her letter."
A spokesman for the First Minister and deputy First Minister said the leaders had the first sight of the letter on Monday.
"We welcome the commitment by the Prime Minister to full engagement with the Executive in the UK’s exit from the EU.
“Ministers had first sight of this letter on Monday and given the joint nature of the Executive Office the First Minister and deputy First Minister met at the earliest possible opportunity on Monday following Assembly Business to discuss the contents. We later discussed the letter with the Secretary of State at 5pm.
“While others choose to play to the gallery, talking about kicking down doors we will continue to work constructively to represent the needs of all our people.
“Next Monday we will walk through the door of Downing Street with the mandate the electorate gave us to discuss these matters directly with the Prime Minister and representatives from Scotland and Wales.”
Alliance MLA Stephen Farry has said more concrete assurances are needed from the Prime Minister.
Dr Farry said it was "disappointing" that the reply was revealed in the media despite a Brexit debate in the Assembly on Monday.
He said: “This letter is just words, which do little to address the specific issues raised by the First Minister and deputy First Minister, let alone the many other issues facing Northern Ireland, which they failed to raise in their original letter.
“It is natural for the UK Government to say they don’t want to see Northern Ireland suffering from the loss of free movement of people and goods or the loss of structural funds. But the big contradiction are the comments from that same Government over the past few weeks, which suggest they will be pursuing a hard Brexit.
“Any such process would make it even more difficult to achieve the aspirations the Prime Minister has expressed in her letter. In that context, active consideration must be given to giving special status to Northern Ireland. However, we require more concrete assurances as to the specific measures that can be considered to help this region.
“Once again, it is disappointing we are hearing developments relative to Brexit in the media first, instead of the chamber. There is a major accountability deficit from the First Minister and deputy First Minister, who have yet to even mention the Prime Minister’s response to the Assembly.”