The rising cost of chocolate, butter and eggs has helped drive food price inflation to its highest in 18 months, a survey says.

Food inflation hit 4.2% in the year to August, up from 4% in July, according to the British Retail Consortium’s latest shop price monitor. It said food prices were rising at the fastest rate since February of last year.

The figure echoes separate recent data from the Office for National Statistics, which found the cost of everyday food items rising by a similar amount over the last year.

Helen Dickinson, the BRC’s chief executive, said there was some respite for parents as the new academic year approaches, with cheaper clothing, books and stationery.

Ms Dickinson said staples including butter and eggs had seen “significant increases” due to high demand, tightening supply and increased labour costs.

“Chocolate also got more expensive as global prices of cocoa remain high owing to poor harvests,” she said.

Poor cocoa harvests have been caused by climate change and crop disease.

“There was some respite for parents ahead of the new academic year, with lower prices for clothing, books, stationery, and computing.”

Mike Watkins, head of retailer and business insight at NIQ, which compiles the BRC’s shop price monitor, said the uptick reflected “several factors”.

These included global supply costs, seasonal food inflation driven by weather conditions and a rise in underlying operational costs.

“As shoppers return from their summer holidays, many may need to reassess household budgets in response to rising household bills,” he added.

Kate Rumsey, owner of Rumsey’s Chocolaterie in Thame, Oxfordshire, said chocolate inflation had been “consistently high” for a couple of years.

Her business bought chocolate at around £4,000 a tonne in 2023 but prices have since trebled to about £13,000 a tonne.

The shop has also been hit by higher staff costs, as well as ingredients, such as eggs and butter, becoming more expensive.

Ms Rumsey said the business absorbed most of the higher costs, but added she had to pass some costs onto customers, with prices up 10 to 20% depending on the product.

In some cases, she said the business had removed some products off its menu due to them becoming too expensive to produce.

Increasing food prices added to increase in overall inflation in the year to July.

The latest official figures from the ONS put UK inflation – as measured by the Consumer Price Index (CPI) – at 3.8%, up from 3.6% in June.

Looking over the longer term, the picture is even more stark.

In the five years to July, food prices increased by around 37%. That compares with a rise of 4.4% over the previous five-year period.