A senior civil servant is taking legal advice about whether he can comply with an instruction from a Stormont minister to stop work on permanent facilities for post-Brexit trade checks.
Agriculture department permanent secretary Denis McMahon confirmed the move when speaking to MLAs at Stormont.
Last week Agriculture Minister Gordon Lyons ordered a halt to work on border control posts in Northern Ireland.
Mr McMahon said he expected to have the legal advice within days.
He told the Stormont Agriculture Committee that advice would inform a paper about the issue that the minister would take to the Stormont executive next week.
The border control posts are used for carrying out checks on goods entering Northern Ireland from Great Britain.
Mr Lyons' instruction was for a stop to the work on the border posts and the recruitment of extra staff as well as a pause to a charging policy for businesses using the system.
He cited a lack of clarity about the nature of infrastructure that would be needed in light of ongoing negotiations between the UK and the EU about the level of checks.
He also said that was uncertainty caused by legal challenges to the Northern Ireland Protocol, the post-Brexit trade arrangements for Northern Ireland.
Some of Thursday's session focused on the level of checks required by the Northern Ireland Protocol and the capacity of staff here to process them.
Trade in food inside the EU doesn't need complex certification, but food imports to the EU's Single Market do.
Under the protocol, trade in food from GB to Northern Ireland is essentially treated as an EU import.
In January and February, thousands of lorries carrying food and plants came into Northern Ireland from Great Britain.
Denis McMahon told MLAs the level of documentary checks required was around one fifth of those carried out by all other EU member states on imports from third countries.
The Chief Vet, Robert Huey, said if new arrangements weren't forthcoming when the grace periods ended, Northern Ireland would be doing as many documentary checks on GB to NI trade as the rest of the EU did on food imports from third countries.
And he said with just 12 vets doing the job at present, that wasn't sustainable.
Irish Sea border checks are continuing at the temporary facilities and the permanent ones are not expected to be completed until the middle of 2022, MLAs were told.
Mr McMahon also set out the huge number of checks that were being carried out in the temporary facilities - something he described as a huge challenge.
He also pointed out that, due to the grace periods allowed as part of the Northern Ireland Protocol, much of the required certification for supermarkets had been postponed and he was not sure he could get the staff needed to do all that work when it came into effect.
Northern Ireland's chief vet Robert Huey said Mr Lyons' decision to pause work on the permanent facilities and recruitment had had an impact on staff morale.
He said while the temporary facilities were good, some of them were "tents" and he questioned whether he could ask his staff to spend another winter in them.
He also said he needed more staff to relieve those working on shifts who had been looking forward to additional colleagues joining the team as "the cavalry coming over the hill".
MLAs were also told there had been no meaningful consultation with officials in Northern Ireland prior to the announcement by the UK government on Wednesday of a unilateral extension of the grace period for the certification required for supermarket goods moving from Great Britain to Northern Ireland.