One of the UK's top organic health product firms has warned that post-Brexit barriers to trade are threatening the supply of organic goods north and south.
Ken Moody of the Health Made Easy Group, which supplies more than 300 retailers across the island, said millions of pounds of trade was at risk, as well as the survival of many small businesses.
He said the cumbersome bureaucratic processes the company was now faced with could cost almost a million pounds in extra certification and additional administrative costs - and "at a stroke make the trade commercially unviable".
For every consignment of organic products, he said a Certificate of Inspection (CoI) had to be created for each product in the consignment - and there could be up to 500 different products per single consignment.
The firm expected to make 10,000 consignments to Ireland per year.
Currently, a CoI costs £25, plus administration costs, and Mr Moody estimates each CoI will cost at least £50 in extra costs - meaning a potential bill of £750,000 to cover the cost of all the certificates needed under the new regulations, plus a further £200,000 to cover additional customs administration.
"Our customers are absolutely up in arms," he said.
"Their businesses are at risk, and if we can't find a solution relatively quickly, not only will consumer choice be affected, but the existence of these local retailers - who've been around for decades - will be tested."
Mr Moody said: "We're being told that we can't ship organic products from GB to Northern Ireland, and shipping products into the Republic is a complete no-no."
His warning over organic products came as a leading garden centre owner said Northern Ireland's horticulture sector faces "disarray" this spring due to post-Brexit trading rules.
Robin Mercer, owner of Hillmount Garden Centre in Belfast, called for Government help.
Northern Ireland has remained in the EU's plant health system, meaning NI must apply EU rules on all horticulture products entering from GB.
Some plants now need a health certificate before they can enter Northern Ireland.
Other products have been completely banned, including soil as it can carry pests.
Some businesses in the UK have already halted sales to Northern Ireland customers.
"The whole thing is ridiculous," Mr Mercer said.
"We have been ordering the same plants, bird food and gardening tools for years and almost overnight a wooden-handled trowel cannot be delivered to us.
"Roses can't be shipped due to how they are grown. Yet one supplier in GB is saying they can ship our order to Europe and drive it to us via the Republic.
"Where is the sense in that?" he asked.
The Department for Agriculture has been contacted for comment.