UK MPs have clashed over fears about the North's border with Ireland in the wake of the vote to leave the EU.
The SDLP's Dr Alasdair McDonnell warned that the uncertainty about the border could erode the fragile political settlement and lead to renewed dissident and paramilitary activity.
The North’s shadow minister Stephen Pound insisted that a Brexit would result in a "division" between the two countries.
But DUP MP Sammy Wilson said concerns about border controls were just another scare story "without any substance".
In a Westminster Hall debate in Parliament, Dr McDonnell stressed the need for the UK government to guarantee at least one representative for the North at the Brexit negotiating table.
The North may also have to make "common cause" with Scotland and Gibraltar, whose populations also voted to remain with the EU, he added.
The Belfast South MP said: "I believe that Northern Ireland's interests cannot receive the full recognition or the full protection they deserve unless Northern Ireland has at least one, preferably two, seats at the negotiating table as we go forward."
He added: "Further uncertainty around what the border will look like in 10 years' time leaves us vulnerable to those that will seek to take advantage of that uncertainty and weakened state, including dissident and other paramilitaries.
"And I don't make that as a threat - I make that as an observation."
Labour's Mr Pound, a pro-Remain campaigner, said the Government must accept the "dark clouds over Northern Ireland".
He said: "If anyone thinks for a moment that the history of Ireland somehow means that there will not be a hard border, a soft border, a customs border, a tariff border, a physical border - there will be a border.
"There cannot be a negotiation when one party has decided to leave the relationship. That is the reality."
But Mr Wilson said there had so far been no political appetite for new border controls.
The East Antrim MP said: "This is one of the scare stories that was used by those who have tried to persuade people in Northern Ireland that leaving the EU is not in their interests.
"Again we have heard the same rhetoric but there is not substance to it.
"The Irish Government has said they do not wish to have border controls, the British government has said they do not wish to have border controls, the Northern Ireland Assembly has said they don't wish to have border controls and we already have seen through history how the common travel area has worked effectively to ensure that there is no need for border controls."
UK home office Minister Robert Goodwill said Ireland and the share a common objective of preserving the common travel area and avoiding a hard border.
He said: "It has been agreed that the UK and Ireland would work together on priority areas within the British-Irish relationship in the forthcoming negotiations on the future relationship between the UK and the EU.
"The government will ensure the interests of all parts of the UK are protected."