British small businesses have hit out at newly announced post-Brexit import fees coming in later this month, warning they could wipe out profits and make importing some products unfeasible.

Trade bodies, retailers and small firms said that the new charges of up to £145 for each consignment could force them to limit the range of items they can offer, while others may have to push up their prices.

The comments come after the government published much-anticipated details of how much importers of plant and animal products would have to pay for checks on goods coming into the country through Dover and the Eurotunnel. The checks will be introduced on 30 April as part of the government’s Border Operating Model, which aims to mirror the checks already in place on products entering the EU from the UK.

The charges, which are capped at £145 for mixed consignments, will see importers of “low risk” goods paying £10 for each product line, while those bringing in medium and high-risk goods, which include most meat, dairy and plant products, will have to pay £29 for each item type. This means a small shipment containing just five different types of meat, poultry, egg, milk or plant products would incur the maximum bill.

Trade bodies condemned the additional financial burden for struggling small businesses, arguing it would disproportionately affect them as they were more likely to be importing small mixed consignments.

Nigel Jenney, the chief executive of the Fresh Produce Consortium, said the changes will mean small businesses having to pay thousands of pounds extra on a weekly and monthly basis. “This may mean reducing the range available for customers, or simply accepting the costs, which the consumer will have to fund, and lead to food inflation, caused solely by the UK government,” he said.

Marco Forgione, the director general of the Institute of Export & International Trade, said: “While larger businesses have the capacity to absorb this cost, it will be small businesses that will feel the full force of these charges. Up to an additional £145 a consignment might mean entire profits wiped out completely.”

The Horticultural Trade Association said small plant sellers would usually be importing more than five product lines, meaning they would incur the full charge for each delivery.

Helleentje Walker, from Wack’s Wicked Plants in Scampston, Yorkshire, said the new charging regime would make it “unfeasible” to bring in some products from the continent. Her company ordered a year’s worth of plants earlier this year, in a decision partly driven by the new charges.

Andrea Rasca, the chief executive of the London food market chain Mercato Metropolitano, said the new fees and time-consuming checks would discourage businesses from Europe sending goods to the UK, reducing the products it could offer at its sites.

He said about 60% of its suppliers from Italy had already stopped sending goods to the UK because of the additional administration and costs since Brexit.

The announcement of the charges comes just weeks before the government implements the new border checks, with businesses complaining that the details should have been published months ago.

Richard McKenna, the managing director of Provender Nurseries in Kent, said it had been unable to quote customers for any jobs past May as a result of the business not having sight of the common user charge fee. He said: “We have probably lost work because we haven’t quoted because we haven’t known the cost.”

The Federation of Small Businesses chair, Martin McTague, said: “Although we knew these changes were coming in at some point, formally announcing an onslaught of more fees with less than a month’s notice will undoubtedly cause a great deal of stress.”

The government said: “The charge is designed to recover the costs of operating our world-class border facilities where essential biosecurity checks will protect our food supply, farmers and environment against costly disease outbreaks entering the UK through the short straits.

“The charges follow extensive consultation with industry and a cap has been set specifically to help smaller businesses. We are committed to supporting businesses of all sizes and across all sectors as they adapt to new border checks and maintaining the smooth flow of imported goods.”