Hauliers are warning that large retailers could cut back on shipping to Ireland if checks created by Brexit cause delays.
Martin Reid, the RHA's director for Scotland and Northern Ireland, slammed the government this week for failing to clarify the nature of post-Brexit customs checks.
Reid said the situation at the port of Cairnryan, in Dumfries and Galloway, where many goods are transferred between Scotland and Northern Ireland, is unclear - whether or not a Brexit deal is struck.
"Although we got some announcements on the Northern Ireland Protocol, the minutia and the detail are still to be decided, there's still more to come," he said.
"On one hand we've heard that some major retailers will scale back movements to Ireland.
"We've heard of one in particular who may not go near it for the first three months of the year.
"We've also heard contrary stories that it could increase the volume."
He warned Scottish producers may struggle to get time-sensitive goods to mainland Europe quickly enough which could result in chilled foods such as fresh shellfish being dumped, if it cannot get to crucial markets in France on time.
In a statement the RHA added: “Although it was revealed this weekend that Brexit negotiations between the UK and EU will continue until 30 December 2020, there is still precious little clear, actionable information being released by the UK government, and even less time in which to act on it.
“We will be continuing to put pressure on the UK government to release the vital information for which the UK’s haulage and logistics industries have been crying out.”
