Grocery price rises gained pace over the month to August 4 for the first time since March last year.
According to Kantar analysts, prices across Britain’s supermarkets climbed by 1.8% over the period, against 1.6% a month earlier.
“Having reached its lowest rate in almost three years in July, August saw inflation nudge up again slightly,” Kantar retail and consumer insight head Fraser McKevitt said.
“While this is noticeable following 17 straight months of falling rates, it actually marks a return to the average levels seen in the five years before the start of the cost-of-living crisis.”
Kantar added that prices rose across 182 product categories and fell among 89 others, with spending on special offers rising over the month.
Wine and beer sales benefitted from the Olympic opening ceremony and Euros respectively, as some £10 million was spent on the latter in supermarkets on the day of the final.
J Sainsbury PLC (LSE:SBRY) recorded its largest annual market share gain since 1997, of 0.5%, Kantar said, while Tesco PLC (LSE:TSCO) and Ocado Group PLC (LSE:OCDO) also scored higher sales.