BORIS Johnson's proposed all-Ireland economic unit could lead to a political united Ireland, a former loyalist paramilitary prisoner claimed.
Mr Johnson has denied that his draft Brexit deal with the EU would create extra customs checks on goods travelling between Britain and the north.
That assertion has been challenged by the Labour Party during the general election campaign.
Gary Blair is a rural unionist from Co Antrim opposed to these checks.
He addressed an Open Doors discussion event on Irish unity and the impact of the UK's EU separation involving former prisoners from the Northern Ireland conflict.
Mr Blair said: "We never joined the EU, we joined the common market, an economic market, not a political powerhouse where we surrender sovereignty to a foreign power in return for less than we put in."
In 1973 when Britain joined the European Economic Community it was a common market, countries seeking to help each other, he said.
"It was never a political force.
"The superstate morphed into something that we were never part of.
"The fear now is, being pro-Brexit, that that economic or agreement back in the early 1970s somehow became a political force and a political unit.
"Johnson's border in the Irish Sea will put Northern Ireland and the Republic of Ireland as an economic unit.
"Our fear would be how long will it be before it becomes one political unit?"
Colin Halliday, project coordinator with the Charter NI organisation, is part of the Open Doors project and anticipates changes following Thursday's general election.
He said: "We are going to be more polarised.
"We heard from the loyalists who were speaking there, they have great difficulties with their political people who are in the DUP, but in all honesty I think Sinn Féin get the DUP elected because of their policies.
"Open Doors is a great opportunity for loyalists and republicans from different shades to come together, have their talks, that was brilliant tonight, we need to get that back into loyalist communities and I believe we will, to get republicans to come and feel confident.
"Jaw jaw is better than war war and that is what we were saying in there clearly.
"We want to engage, we want to move forward, let's have a debate about a united Ireland but also about staying part of Britain, which clearly came across today and republicans were hearing that."
Paul Gallagher from the republican ex-prisoners group Teach Na Failte said people honestly conveyed their positions.
"The honesty was very respectful, I think the whole presentation was from a position of giving an understanding of where different groups are coming from but they can do it through a very good process of dialogue and getting an understanding of other people's perspectives."
