Northern Ireland farmers have called on the government to match the EU's tariffs on agricultural produce to protect the industry in the event of a no-deal Brexit.
In March, the UK government announced a temporary tariff schedule that would apply in such circumstances.
The year-long arrangement would see tariffs retained on imports to the UK of sensitive agricultural imports.
These would include beef, lamb, pork and poultry.
But these would not apply at all on imports from the Republic of Ireland to Northern Ireland to prevent the need for border checks.
However, foodstuffs going the other way across the border would face EU tariffs, if there is no deal.
There is a substantial existing cross border trade in things like milk, sheep, pigs and cattle.
Now, the Ulster Farmers' Union (UFU) says that in order to protect the food industry in Northern Ireland, import tariffs will be needed if there is a no-deal Brexit.
President Ivor Ferguson said it would be a "catastrophic" outcome for farming and food production.
"Steep export tariffs, additional checks and regulations, combined with a proposed zero tariff on agricultural goods from ROI to NI, will result in significant disruption and pose a logistical nightmare for farm businesses."
Mr Ferguson said if the EU imposed tariffs on UK exports, the government should reciprocate at the same level.
Failure to do so would drive down prices and create a black market for smugglers which could threaten the integrity of both Northern Ireland and the UK's agri-food industry.
"Farmers are the industry's bedrock and everything must be done to ensure the future viability of family-run farm businesses," Mr Ferguson said.
A Northern Ireland Office spokesperson said: "Whatever the course of events, this government will never create a hard border on the island of Ireland and will never put physical checks or physical infrastructure on the border.
"We are steadfast in our commitment to protecting the Belfast ('Good Friday') Agreement and fully recognise the unique differences between the needs of Northern Ireland's economy and that of other parts of the UK.
"In line with that policy, goods moving from Ireland to Northern Ireland are exempted from the UK's temporary tariff.
"We will continue to work closely with businesses to ensure they are fully prepared to leave the EU by 31 October, whatever the circumstances."