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Nick Clegg MP
Nick Clegg, the Liberal Democrats' EU spokesman, has warned that the
Clegg, who has worked as an EU trade negotiator, told the Financial Times that the levies are likely unless the UK remains in the single market, or strikes a bilateral trade deal with the EU.
Food prices became a headline Brexit issue last week when many popular UK brands, including Marmite spread, were removed from supermarket shelves following a dispute over prices, after the pound fell rapidly.
"It's clear that Marmite was just the tip of the iceberg," Clegg said.
"A hard Brexit will lead us off a cliff edge towards higher food prices, with a triple whammy of punishing tariffs, customs checks and workforce shortages," he added.
Clegg believes that Britain should stay in the single market and seek a deal based on Norway's model, in which it contributes to the EU budget.
If the UK pursues a "hard Brexit" and leaves the single market the UK would likely be subject to the EU's trade terms with the World Trade Organisation (WTO). That includes an average tariff of 22.3% on agricultural products and 2% on non-agricultural products.
Some levies for EU imports to the UK would be far higher than that, however. If the UK does fall back on WTO rules, as Liam Fox has implied it will, levies would include 13% on salmon, 14% on wine, 40% on cheese, and 59% on beef.
May has refused to rule out remaining in the single market, but her hardline stance on immigration will make it difficult. EU officials have repeatedly made it clear that the UK cannot stay in the single market if it wishes to curb EU immigration.