Some businesses near the Irish border have begun making contingency arrangements for a hard Brexit, traders said.
Newry in Co Down will be the closest UK city to the EU after March 29. It is just a short journey from the frontier and is on the main route between Belfast and Dublin.
Colm Shannon, chief executive of Newry Chamber of Commerce and Trade, said preparations would include stockpiling and considering alternative routes to market.
He added: “All businesses will be looking at their supply chains, bigger companies have put in place contingency arrangements.
“Some have started to enact those arrangements, it has gotten too close to 29 March to wait.”
Mr Shannon said the challenge was particularly acute for manufacturers, who operated on a just-in-time supply model and had limited margins for extra costs produced by delays at the border.
The agri-food industry also has concerns about accessing the Great Britain market via the Dublin to Holyhead ferry sailing, the business leader said.
He said firms were more aware of the advice and support from the Irish Government, which he said had been much more aggressive in providing that support, but acknowledged the work of authorities in Northern Ireland to give information.
The cross-border InterTradeIreland body is based in Newry.
Mr Shannon added: “We are going to be the closest UK city after Brexit to the land border with the EU and our concern is what the shape of that land border might be and what impact it might have on the local economy.
“Back in the 1980s, unemployment was sitting here at 27%.
“As a result of no hard border, the peace process and access to open markets we are now sitting at virtual full employment in the area and our real concern is that a border, no matter if there is no physical infrastructure, just the perception of the border would impact on trade and businesses in the border area.”