The prospect of a return to border controls between Northern Ireland and the Republic as a result of a Brexit is both "repulsive and upsetting", a British Labour politician has said.
Claims by Northern Secretary Theresa Villiers that the common travel area between the UK and Ireland would be unaffected are wrong, Conor McGinn, MP for the St Helen's North constituency in Merseyside, said.
Mr McGinn, who is originally from south Armagh, claimed 'leave' campaigners were being disingenuous in their statements about the North.
"As someone who grew up six miles from the border during the late 1980s, 1990s, I can categorically say that the idea of going back to any sort of restriction, or even the word checkpoint, in the border between north and south, is both repulsive and upsetting," he said.
He was speaking on a panel discussion at the University of Liverpool, along with Foreign Affairs Minister Charlie Flanagan, Hilary Benn, Shadow Foreign Secretary, and Grainne Mellon, co-chair of the Irish4Europe campaign.
Mr McGinn said it was not overstating, or scaremongering, to say the progress that has been made on both sides of the border would be put at risk.
Asked by a member of the audience about claims from the leave side that a border would not be reinstated, Mr McGinn said they were wrong.
He said Brexit could ultimately mean a hard border between the island of Ireland and Britain, meaning someone travelling from Belfast to Liverpool would need to go through passport control.
Mr Flanagan said that if a Brexit were to occur, at best there would be huge uncertainty around the border issue.
At worst, there wold be border controls that would give "rise to serious adverse consequences in terms of trade and economic engagement".
The minister is on a two-day UK visit to engage with members of the Irish community ahead of the crucial referendum on June 23.
As well as taking part in the Institute of Irish Studies discussion at the University of Liverpool, he did a site visit with ABP foods and visited the Irish Heritage Centre in Manchester last night. Today he will speak at a British Irish Chamber of Commerce event in the city.
Mr Flanagan said it was important for those with a franchise in the UK to register to vote, and he said for Ireland, the Government believes the UK is better in the EU.
"I know that for some voters the Irish perspective may be one of the factors they consider when informing themselves about the issues concerned," he said.
Mr Benn said the vote is the most important decision of a lifetime. And he said in the EU, the UK wields great influence.
Research carried out by Irishjobs.ie and NIjobs.com showed that 42pc of Northern Irish and 41pc of Irish employees fear the reintroduction of border controls. And 77pc of Northern Irish employees believe a Brexit would push the UK economy into recession.
Meanwhile, in the Dáil Taoiseach Enda Kenny has warned that a Dáil motion calling for Irish people in Britain to vote 'remain' could backfire.
But Mr Kenny said the Government is actively encouraging Irish citizens with a vote to help avoid a Brexit.
He was responding to a suggestion from Labour Party leader Brendan Howlin that the Taoiseach organise an all-party motion, signed by every TD, "calling on Irish voters and those with Irish connections in the UK and an entitlement to vote and UK citizens living in this jurisdiction to vote to stay in the EU".
"This is of such vital importance to us," Mr Howlin said, adding that the debate could explain to Irish voters how Britain staying in the EU is in our "strategic interest".
However, Mr Kenny said he would need to "reflect" on the proposal. "It might not have the effect that you intend," he said.