Sales on the high street edged up by just 0.1% in July, according to official figures.
Warm weather in the final week of the month helped support food and drink sales, the IGD said, but a sharp fall in food inflation kept a lid on overall growth.
In the three months to July, food sales were up 3.8% against a year ago, or 0.9% on a like-for-like basis.
“July was clearly not a golden month for retail,” said Stephen Robertson of the British Retail Consortium.
“Like-for-like sales were virtually flat compared with a year ago and total growth of 2% was still behind inflation as consumers, dealing with squeezed budgets, prioritised their spending on essentials.”
“There was a boost for food retailers towards the end of the month as the sunshine came out and shoppers started getting in party food and drink ahead of the Olympics but it wasn’t a significant help.”
Helen Dickinson of KPMG added: “Early expectations that the Olympics will raise retailers’ fortunes look to be wide of the mark. London’s retailers are already being hit hard by shoppers actively avoiding the capital. It’s likely that any blip of benefit the games bring will be short lived.”