Border controls with the North would be reimposed if Britain left the European Union, a British government report has stated.
The cabinet office report on the consequences of leaving the EU also warned that the future of the common travel area would be in doubt.
"Northern Ireland would be confronted with difficult issues about the relationship with Ireland. Outside the EU's customs union, it would be necessary to impose customs checks on the movement of goods across the border. Questions would also need to be answered about the common travel area which covers the movement of people," the report notes.
Cameron warning
The impact on Northern Ireland is among the negative consequences of Britain leaving the EU identified in the 28-page report, which warns of a decade of uncertainty.
Prime minister David Cameron warned last week about the impact of leaving the EU on jobs and farm incomes in the North.
During a visit to Northern Ireland yesterday, London mayor Boris Johnson, who is campaigning for Britain to leave the EU, dismissed fears and said the North had everything to gain from leaving. He said he thought it would be good news for fisheries and farming and that "the subsidies would be better tailored to their needs".
