The EU should allow vital concessions like zero tariffs in a spirit of generosity during trade talks, retailers in Northern Ireland have said.
Higher costs and less availability will hit the region hardest unless extra measures are taken to mitigate the effects of Brexit, the Northern Ireland Retail Consortium (NIRC), which represents larger businesses, said.
It urged the UK Government to establish import and export processes and all necessary infrastructure now.
Director Aodhan Connolly said: "We need the UK government to work with us to deliver key mitigations that could reduce the impact on consumers and retailers. And we need a generosity of spirit from the EU to allow these mitigations to happen."
The lobby group called for pragmatic solutions on compliance and regulatory checks that will apply from January 2021 as the Brexit transition period ends.
Almost 80% of all the food that UK retailers import comes from the EU, making the negotiations particularly important for such essentials, traders said.
Mr Connolly added: "Without the mitigations recommended within this report, there will be higher costs and less availability for Northern Ireland consumers and this will hit us hardest.
"We already have half of the discretionary income of Great British households and so our households in Northern Ireland simply can't afford these cost rises.
"We are talking about costs that have simply never been there before.
"It is a simple equation that if the new costs are higher than the profit margin then either the product or that particular business model needs to change or becomes unviable.
"We also already have between 12 and 18 hours' less shelf life on some products than shops in Great Britain due to our geographical location. Any further delays affect availability."
Measures the lobby group is seeking include:
π A zero tariff trade deal.
π Co-operation with the EU to minimise trade friction.
π Coordination on VAT, customs and excise procedures.
π Advance information on new checks and paperwork, and
π Timely construction of necessary infrastructure at UK ports.
Meanwhile, the French government has warned London to prepare for a bitter, bloody battle in the Brexit trade talks with the EU. French foreign minister Jean-Yves Le Drian yesterday bluntly said the two sides would "rip each other apart".
These comments follow warnings from Boris Johnson late last week that there would be "no border in the Irish Sea", raising concerns about the durability of no visible border between Ireland north and south.
Brussels diplomats are working on ground rules for negotiations on future EU-UK relations in talks due to start next month. But London and Brussels have already clashed over rules for British financial firms' access to the EU after Brexit.
Mr Le Drian said it would be tough to achieve Britain's aim of agreeing a free trade deal by the end of the year, with the two sides far apart on a range of issues.
"I think that on trade issues and the mechanism for future relations, which we are going to start on, we are going to rip each other apart," he told a security conference in Munich yesterday.
"But that is part of negotiations, everyone will defend their own interests."
Britain finally left the EU on January 31 but nothing has yet changed because of a transition period due to last until the end of this year.
France is among eight nations, including the Irish Republic, concerned about continued access to UK fishing grounds.
Irish boats take up to one-third of the value of the Irish catch in these waters and the potential loss to the Republic could run to €500m per year with the extra loss of more EU vessels piling into Irish waters.
For London the amounts at stake are relatively modest. But fishery waters are a big political issue going back decades and the UK wants full autonomy and limited access for European fishermen.