EUROPEAN Commissioner Phil Hogan has said a UK exit from the European Union could lead to an increase in cross-border smuggling and illegal trade.
The powerful commissioner for agriculture and rural development said there would be "clear incentives to recreate the old channels of smuggling across the border", with increased costs for both states to deal with the problem.
He said any new land border could also disrupt the substantial trade in agri-food products and damage relationships between businesses north and south.
"I believe that it would be a retrograde step if that relationship was compromised by the potential tariffs, tailbacks and other trade blockages that an external border would entail."
Giving the annual 2016 Gibson Lecture at Queen's University yesterday, Mr Hogan stated his belief that a shared European Common Agricultural Policy (CAP) remains the best way forward.
"CAP Single Farm Payments to farmers in Northern Ireland is worth in excess of £2.3 billion from 2014-2020," he said.
"To put that figure into perspective, annual payments from the European Union account for 87% of annual farm incomes, compared to 53% in the UK as a whole.
"In other words, for every £10 sterling that Northern Irish farmers earn, the Common Agricultural Policy accounts for £8.70 of that total.
"To put it more bluntly, were it not for European assistance, many farms would not alone generate significant losses, but would struggle, and in many cases fail, to survive."
In terms of international trade, Mr Hogan - one of 28 European Commissioners, with responsibility for setting and managing EU policy - stressed the importance of the size and strength of European Union in negotiations.
The Kilkenny-born former Fine Gael TD also spoke of the "significant positive impact on the daily lives of everyone living in Northern Ireland" of the European Union and its importance to the peace process.
"While the politicians and citizens of Northern Ireland are responsible for the tremendous progress made over the last 20 years, I believe that the EU can take some credit for helping to 'bed-in' that peace.
"European programmes have helped communities of different traditions to come together and increase their understanding and appreciation of one another's positions, traditions and history."
Accepting that the current Common Agriculture Policy needs to be "simpler and fairer", he said there was no viable alternative in place at present.
"Those in favour of leaving the EU argue that the UK can design an agricultural policy which will serve the interests of both the farming community and society at large better than the CAP.
"This is perfectly true as an untested hypothesis. But to the best of my knowledge no-one has put any flesh on the bones of this claim.
"Any plans outlined so far would see a significant cut in support to farmers of up to a third, with knock-on effects across the rural economy as a whole."
The commissioner added: "There is no comparable agricultural policy scheme on this planet, either existing or hypothetical, than can continue to deliver for the farmers, rural communities and citizens of Northern Ireland better than the CAP."
