Northern Secretary Theresa Villiers has insisted Britain is not "dashing" to exit the European Union.
Meanwhile, a senior Scottish MP has raised the "nightmare scenario" of Scotland exiting the UK and the rest of the union voting to leave the EU.
Concern about Britain quitting the EU was a key focus at the second annual conference of the British Irish Chamber of Commerce held in the Titanic visitor centre in Belfast yesterday.
With Ms Villiers in the audience, Minister for Public Expenditure and Reform Brendan Howlin warned against the UK leaving the EU.
"I believe that a union without the UK would be the poorer for that. I believe the UK would be the poorer and I believe Northern Ireland would be the poorer," he said. "The UK has a place at the centre of the union. The union has benefitted from UK membership and I believe the UK will continue to benefit from EU membership."
Ms Villiers also addressed the Chamber of Commerce, which was established on the back of Queen Elizabeth’s visit to the Republic in 2011.
Ms Villiers spoke to reporters on the margins of the conference about the potential for Britain voting itself out of the EU.
'Exit door'
British prime minister David Cameron has pledged that if his Conservative Party is returned to power in next year's Westminster elections he will seek reform of the EU and then put a referendum on Europe to the people.
“I just don’t think Britain is dashing for the exit door,” Ms Villiers said.
“ I know that some of the commentators feel that that is the case and that there is anxiety about that in Republic of Ireland,” she said. “That is not the prime minister’s goal, his goal is to reform our relationship with Europe and then give people in UK the vote on Europe that they haven’t had for 40 years.”
However, it was clear at the conference that there are political and business apprehensions about a UK exit from Europe.
The Scottish Liberal Democrat MP Charles Kennedy referred to the possible "nightmare scenario" of first Scotland exiting from the UK in September's referendum and subsequently a Conservative government holding a referendum in which the majority of people in England, Wales and Northern Ireland voted to quit the EU.
He was hopeful this would not happen but said people must not be complacent about the possibility.
“Where would we be then?” asked the former Liberal Democratic leader. “That is the nightmare scenario; let’s hope it doesn’t get there. It will be up to all of us to make a persuasive case both from the head and the heart to ensure that disastrous set of consequences doesn’t unfold.”
'Red meat'
Mr Kennedy said there was no placating Eurosceptics short of disengagement from Europe. "You can throw them as much red meat as they can devour it and they will still come back for more and eventually they will devour you," he said.
Former Ireland rugby international Hugo MacNeill, Ireland director of global investment firm Goldman Sachs, warned that in addition to the repercussions for the Republic, quitting Europe would have particular consequences for Northern Ireland.
He said “alarms bells” should be ringing for Northern business people who traded with the EU and the rest of the world. “Do people fully understand the issues?” he asked. It was important that Northern Ireland had a “coherent voice” .
