Supermarket shoppers will be hit by price rises of at least 5 per cent over the next year, the former head of Sainsbury's has warned.

Justin King blamed the plunge in the value of the pound since Brexit for creating a “profound change” for food retailers.

Mr King said supermarkets would find it hard to calm price hikes while dealing with increased costs.

He told BBC Newsnight: “Something of around 40 per cent to 50 per cent of what we buy in the shops is sourced abroad in a currency other than the pound, and with the current rates of exchange we could expect that to be about 10 per cent more expensive in a year's time. And if that's about half of what we buy, that means something of the order of 5 per cent inflation.”

The view was supported by the director-general of the Food and Drink Federation, Ian Wright, who told the BBC prices could increase next year by between 5 per cent and 8 per cent.