Fears that Northern Ireland's peace process could be thrown into turmoil in the event of a UK exit from the EU have been blasted by MPs as "shocking" and "utterly disgraceful".
The comments came from both Tory and Labour eurosceptics during a major Brexit debate in Belfast last night.
On the Remain side were Vernon Coaker MP, shadow secretary of state for Northern Ireland, and former MEP and Conservative Party member John Stevens.
On the Leave side were former Northern Ireland Secretary and Conservative MP Owen Paterson, along with Northern Ireland-born Labour MP Kate Hoey.
Concerns over Northern Ireland's security situation were raised during a Government report earlier this year, which said Irish border controls could be reintroduced in the event of a Brexit.
Mr Paterson said the EU referendum was the "largest question facing this country since the Reformation".
"The euro is a nightmare for southern Europe and a huge problem for northern Europe," he added. "Everyone talks about the EU as a nice stable entity... we don't know where this is all going. We really are at a fork in the road."
Mr Paterson claimed the UK should move back to a settlement based on a number of areas, including free trade and security.
And he insisted the EU had little to do with assisting the peace process.
He also echoed comments from Kate Hoey and said fears that peace here could be hit if the EU voted to leave were "utterly disgraceful".
More than 150 people turned out for the event, which was chaired by Jeffrey Peel of Quadriga Consulting and held at the Northern Ireland Science Park in Belfast. It was also streamed live online.
Speaking last night, pro-EU campaigner Vernon Coaker said: "I do believe being in the EU we can achieve more growth, better prosperity.
"It's not trying to promote fear... it's pointing out what being part of the EU means."
Mr Coaker claimed one in eight jobs in Northern Ireland was linked to EU trade and he raised concerns over employment, the potential impact on interest rates and the strength of sterling and what would happen to farm subsidies in the event of a Brexit.
"I'm not saying for one moment that there would be a return to the bad old days," he added. "But the idea that there would be no consequence is the politics of it will be alright on the night.
"What would it mean for people who are trying to come into the EU? (These are) questions that can't be answered. I think the UK has been enhanced and improved by being a part of the EU. There have already been strong signals from the business community and high-profile company leaders that the UK, and in particular Northern Ireland, is better off in the EU."
But two Northern Ireland businessmen, Wrightbus founder William Wright and the boss of pub chain JD Wetherspoon Tim Martin, have voiced strong opinions that the UK should leave.
Last night, Ms Hoey called concerns Northern Ireland's peace process could be impacted by a Brexit as "shocking".
"One of the most annoying and shocking scare stories has come from various politicians - that if somehow we dared the people to leave the EU, that the peace process would be damaged - is a shocking indictment," she said.
Ms Hoey also claimed the EU was "now dysfunctional". "I've seen the changes and many of you will have voted in 1975," she added. "Many of you thought you were voting for a common market, and not what has happened. "We've seen that Europe disappear."
Supporting remaining in the EU, John Stevens, claimed membership was a "reasonable balance" and a "practical compromise". He said being in the world's largest market was key, and he blasted as "ridiculous" claims that leaving would make trade difficult with countries outside the EU.
"Another aspect is the way trade is moving away from goods to services," he said." We are 80% a services economy... it's a hell of a lot more difficult (if the UK leaves the EU)."