Documents from the British government have suggested that Northern Irish businesses consult with Dublin in the event of a no-deal Brexit.
London has published the first batch in a series of notices on how to prepare if there's no deal.
It includes a section on businesses in Northern Ireland, which import and export across the Irish border.
It says: "The Irish government have indicated they would need to discuss arrangements in the event of no deal with the European Commission and EU member states.
"We would recommend that, if you trade across the land border, you should consider whether you will need advice from the Irish government about preparations you need to make."
Today we’ve published the first batch in a series of Technical Notices informing citizens and businesses on how to prepare for the unlikely event of a no deal #Brexit
— Exiting the EU Dept (@DExEUgov) August 23, 2018
It adds: "The UK stands ready in this (no deal) scenario to engage constructively to meet our commitments and act in the best interests of the people of Northern Ireland, recognising the very significant challenges that the lack of a UK-EU legal agreement would pose in this unique and highly sensitive context."
"It remains, though, the responsibility of the UK government, as the sovereign government in Northern Ireland, to continue preparations for the full range of potential outcomes, including 'no deal'.
"As we do, and as decisions are made, we will take full account of the unique circumstances of Northern Ireland."