The pair say they have concerns over drawning down EU funds
The first and deputy first ministers of Northern Ireland have asked to be fully involved in Brexit negotiations.
Arlene Foster and Martin McGuinness have written a two-page letter to the British Prime Minister, Theresa May.
In it, they lay out concerns they have in relation to Brexit, as well as the issues that face Northern Ireland directly.
"The region is unique in that it is the only part of the UK which has a land border with an EU member state," they write.
"We therefore welcome your stated determination that the border will not become an impediment to the movement of people, goods and services."
This reflects previous comments from Mrs May, where she suggested the border between the two countries should not change.
Mrs Foster and Mr Martin reiterate that the border is vital for business, saying: "We therefore need to retain as far as possible the ease with which we currently trade with EU member states and, also importantly retain access to labour."
They also emphasise the impact EU funding has had on the region - Northern Ireland has received funding to the tune of €13bn since 1994.
The pair say they plan to draw down a further €3.5bn between 2014 and 2020.
"The current uncertainty around the ability to drawn down a proportion of these funds, and the absence of EU programmes in the future is of real concern to a range of sectors."
Concluding, Mrs Foster and Mr Martin say: "We have had constructive initial discussions with the Irish Government...and wish to play our part in the engagement between the two Governments on the unique aspects of negotiations that arise from the border."
"We wish to have full access to that intergovernmental process as the border issues affecting trade, employment, energy and potential criminality are of such high significance for us."