Mid and East Antrim council chief Anne Donaghy will today give evidence to a Stormont committee investigating the suspension of post-Brexit checks at ports.
Ms Donaghy is before the agriculture committee this morning, along with DUP councillor Peter Johnston, mayor of Mid and East Antrim Borough Council.
Agriculture minister Edwin Poots withdrew department staff from ports at Larne, Belfast and Warrenpoint in early February.
The move to halt inspections came after Mid and East Antrim Borough Council re-deployed employees involved in physical checks at Larne Port following the appearance of threatening graffiti in the seaside town.
It was also claimed that workers' car registrations had been taken down amid loyalist anger over the Northern Ireland Protocol, which has effectively created a post-Brexit border in the Irish Sea.
It is understood that Ms Donaghy told a meeting of party group leaders on the council that the UDA was behind the threats.
Police have said there was no evidence that loyalist paramilitary groups were behind the threatening graffiti or that workers' car registrations had been recorded.
Ms Donaghy is facing increasing pressure to answer questions relating to her council's decision to withdraw 12 environmental health workers from Larne port in February.
Council staff later returned to work.
Department of Agriculture inspections also resumed after separate threat assessments were received from police.
MLAs were told last week that permanent facilities for post-Brexit checks at the north's ports will not be operating before 2023.
Department of Agriculture Permanent Secretary Denis McMahon said the delay was due to ongoing uncertainty over the volume of regulatory inspections that will be required when grace periods limiting red tape end.
Required checks on agri-food goods have been taking place in temporary facilities and repurposed port buildings since the Brexit transition period ended on December 31.
Assistant Chief Constable Bobby Singleton also told committee members last week that it remained the PSNI's position that there were no credible threats to staff.
