SECRETARY of state Theresa Villiers has responded to growing concerns over border controls in Ireland in the event of Britain leaving the EU as "scaremongering".
The Conservative minister is a leading member of the camp backing a so-called Brexit.
She was speaking as leading figures from Irish politics - including former taoiseach Bertie Ahern - voiced concerns about a vote to leave the EU.
Mr Ahern said a UK exit would be "negative in every way" for Britain and Ireland.
And Irish MEP Brian Hayes said a new written declaration between the two countries would be required for trade to continue following a Brexit.
However, Ms Villiers claimed current trade arrangements between the UK and the Republic would be unhindered following an out vote.
Her remarks however appear to contradict those of fellow Brexit campaigner Lord Lawson who said "there would have to be border controls" following a leave vote in the June referendum.
Speaking on Sunday, Ms Villier's however insisted that there would be no changes along the border.
"I believe that the land border with Ireland can remain as free-flowing after a Brexit vote as it is today," she said.
"There is no reason why we have to change the border arrangements in the event of a Brexit because they have been broadly consistent in the 100 years since the creation of Ireland as a separate state.
"It's in the interest of both countries to keep an open border and there's no reason for that to change if the people of this country were to exercise their freedom to vote to leave the EU," she told Sky News' Murnaghan show.
Earlier Mr Ahern had said: "We'd be the only place that has a land border with Britain - of course others would exploit and expose it. They'd have to check people."
He told Sky News: "From a trade point of view it would be a customs border - it's regressive, negative."
On Friday, Mr Hayes pressed the need to establish a stable government in the Republic to prepare for what he called "the real prospect of Britain leaving the EU".
And he suggested the Republic could follow the UK if it did indeed vote for a Brexit.
"We joined with the UK, because we couldn't have joined without them. The question must now be asked honestly; were they to leave now, could we stay in the EU without them?" he asked.
"This is not some academic question. It will have to be faced in a post-Brexit environment. I’m satisfied that we could and should remain in the EU without Britain. I'm satisfied that's it's in Ireland's national interest to remain. But most definitely we would need a new agreement with the EU, post-Brexit. We would also need a new agreement with the UK."
The referendum is set to go ahead on June 23 and polls currently suggest the remain and leave camps enjoy almost equal support.
