Northern Ireland Secretary Theresa Villiers has insisted border arrangements between Ireland and the UK would not change if the public votes to leave the EU.

She dismissed claims that Brexit would prove negative for trade between the countries - and even harm the peace process - as "scaremongering".

Mrs Villiers told Sky News' Murnaghan show that leaving the EU would not alter the free flow of "goods and people" over the only land border with the UK.

She offered reassure after Ireland's former prime minister, Bertie Ahern, voiced strong concerns over the consequences of an Out vote.

He said it would be "regressive" and "negative in every way".


Villiers On Brexit Border Fears

Mr Ahern 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."

Mr Ahern went on: "From a trade point of view it would be a customs border - it's regressive, negative."

But Mrs Villiers, a Brexit campaigner, told Sky News that no changes to border arrangements would be needed.

Ex-Irish PM Issues Brexit Warning

"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."

UK In EU: Key Issues From Campaigns

The border concerns came as Work and Pensions Secretary Stephen Crabb warned that families would face "disastrous" consequences if the UK left the EU.

Mr Crabb, who replaced Out campaigner Iain Duncan Smith in the Cabinet in March, predicts there would be factory closures, an exodus of businesses and job losses.

He said Brexit would cause "economic rupture".

Referendum Push Begins

Writing in The Sunday Telegraph, Mr Crabb warned: "Lost jobs and livelihoods take an enormous, indelible toll on families and communities.

"No one should be complacent about the potential consequences for working people and their families if Britain votes to exit the EU. This is not a theoretical debate."

It is the first official weekend of campaigning ahead of the referendum on 23 June.