Only 60 lorry drivers from Northern Ireland will be able to cross the border in the Republic in the event of a no-deal Brexit, according to a leading trade association figure.
Seamus Leheny from the Freight Transport Association (FTA) said that many lorry drivers in Northern Ireland would be unable to travel into the Republic.
"It's to stop the European market being flooded by haulers from other countries who could possibly do it cheaper and undermine the internal market," he said.
It had been assumed permits would not be needed for Irish cross-border crossing, however, Mr Leheny said Dublin officials had told him they knew nothing about it.
He said some firms had moved to the Republic to lessen the impact. He said a no-deal Brexit would be disastrous for the industry and if they had to rely on permits it would sign the death certificate for many companies.
Applications for international road haulage permits closed last week, with many Northern Ireland drivers failing to apply.
Commercial vehicle operators will need ECMT (European Conference of Ministers of Transport) permits to transport goods to the European Union (EU) and EEA (European Economic Area) if the UK leaves the EU without a deal on 29 March 2019.
Mr Leheny told BBC's Stephen Nolan show the UK as a whole would be given around 1,200 permits, with Northern Ireland getting a maximum of 5% or 60.
He said there were around 20,000 lorry drivers in Northern Ireland, with around 13,000 lorries crossing the border each day.
Mr Leheny said the lack of permits available could be potentially "disastrous" for Northern Ireland.
"It's 100% and it's something we have been banging on about to the government for months now. It's something that other countries have to adhere too, so Turkey, Switzlerland etc are limited the amount of their trucks can enter the EU," he said.
The FTA's Northern Ireland policy manager said mitigation plans had fallen through.
"The system ultimately is stacked against Northern Ireland for two reasons, both legally and technically.
"The legal situation is that the permits bill went before Parliament last year and government signed off on it. When they were putting in the terminology of what classes as a journey to the EU, they said journeys from the Republic of Ireland to Northern Ireland are not European journeys," Mr Leheny explained.
"They have said you will not need a permit for moving goods from the Republic of Ireland to Northern Ireland and vice versa.
"At the time I thought this was great then I ran it past some contacts at the Irish Department of Foreign Affairs and Trade, they came back to me and they said we know nothing about this.
"There's been no bi-lateral deal and no agreement with the EU about this. We still don't have assurances from the EU they would agree to this."
Mr Leheny said the UK Government were in a "panic" over the issue and had asked for the permits to be delayed for nine months to a year. He said the EU were "lukewarm" to the idea.
DUP MLA Jim Wells said the claims were the latest "scare story" to put pressure on politicians to reach a Brexit deal.
"The continentals and the Irish require free trade and movement of lorries for their economic needs.
"I've absolutely no doubt if what this gentleman is saying is true it will be sorted out before March 29, because Europe needs us, it needs our trade."
A Department for Infrastructure spokesperson said that the Department for Transport has responsibility for the permits system but that they are "working with colleagues in DfT and will continue to ensure local hauliers have the latest information as it becomes available".
A spokesperson for the Department of Transport said that The European Commission agreed to propose measures to ensure basic road haulage connectivity between the UK and EU in a communication last month.
"The proposal is that the EU would ensure basic connectivity by allowing UK hauliers’ access to the EU, on the understanding that measures would be put in place by the UK to allow EU haulier’s access to the UK. These proposals are temporary to end 2019 and are currently being considered by the ART 50 Working Group in Brussels."