Around a third of the UK's food is imported from the EU. Carl Court/Getty Images LONDON — Academics are warning the UK could "sleep-walk" into a crisis over food supply post-Brexit, with little signs that the government understands the scale of change and has a plan to cope with it.

Three leading UK food academics on Monday published a paper that warns Brexit could disrupt supply and prices for food in the UK on a scale "unprecedented for an advanced economy outside of wartime."

"The silence about the future of UK food since the Brexit referendum is an astonishing act of political irresponsibility and suggests chaos unless redressed," the report, titled "A Food Brexit: Time to get real", says.

"The country could sleep-walk into a food crisis, unless these problems are acknowledged and addressed."

Professors Tim Lang of City University, Erik Millstone of the University of Sussex, and Terry Marsden of the University of Cardiff authored the 88-page report, saying it is intended to fill the policy gap left by the government.

'Tinned peaches and spam'

A third of Britain's food currently comes from EU countries and the report says there appears to be no government strategy to deal with any shortfall if this supply is disrupted.

"The UK food system, consumer tastes and prices have been thoroughly Europeanised," the report says. "This will be impossible to cut out or back by March 2019 without enormous consequences. The UK food system faces real challenges on food security."

The report adds: "British people often say they want to eat British, but in practice they do something rather different. About a third of UK’s food supply comes from the EU Member States. And over the last half century, tastes have changed dramatically.

"A return to a 1950s or 60’s pre-EU ‘British’ era of food is unlikely. Churchillian romantics who see Brexit as an opportunity to relive Imperial or wartime days go silent if the culinary era of tinned peaches and spam are mentioned."

The report warns that the poorest are likely to be the hardest hit by Brexit, facing a diminished supply of healthy fruit and veg as prices rise due to Brexit.

Food prices could jump by up to a fifth if the UK drops out of the European Union with no trade deal, the report also warns.

Food prices in Britain are already rising in response to the collapse in the pound last year. Food producer output price inflation rose by 5.6% in May, up from just 1.5% at the end of 2016.

Pantheon Economics says in a note sent to clients on Monday: "We think that food CPI inflation rose to 3.0% in June, from 2.1% in May... It likely will continue to rise over the coming months, reaching 5% in Q4."

The below chart from Pantheon shows just how quickly prices are rising:

As well as facing a potential food shortfall if EU trade is disrupted, Monday's report, published by Sussex University, warns that the UK's agricultural industry could suffer from the end of EU subsidies.

The report says: "The UK food system ought to be improving its resilience. It isn’t. It’s like the rabbit caught in the headlights – with no goals, no leadership, and eviscerated key ministries."

Justin King, the former CEO of supermarket Sainsbury's, warned last week that Brexit will mean "higher prices, less choice, and poorer quality" at supermarkets and said consumers at "completely in the dark" about this. Monday's report echoes King's warning.