On a total basis, sales were up 0.1 per cent, against a 2.7 per cent rise in August 2014. Adjusted for the BRC-Nielsen Shop Price Index deflation, total growth was 1.4 per cent.
Clothing, footwear, stationery, furniture, and household appliances experienced declines.
Online sales of non-food products in the UK grew 6.5 per cent in August versus a year earlier, when they had grown 19.8 per cent and established the 2014 best performance. This was the slowest growth registered since April 2013.
The non-food online penetration rate was 17.2 per cent, up from 16.3 per cent in August 2014.
British Retail Consortium director general Helen Dickinson said: "There was better news for food sales this August with a clear improvement compared with July. This, coupled with a positive twelve month average for the first time since August of last year, suggests there may be cause for optimism for food sales following a prolonged period of stagnation.
"While non-food sales over the last three months are up three per cent overall, they were down in August. However the figures were likely distorted by the fact that they do not include the Bank Holiday which will be accounted for in the September period this year.
"At this time of the year parents are busily shopping for back-to-school essentials like clothes, footwear and stationery and those sales will peak later this year. Large ticket item categories like furniture and household appliances also experienced a decline in sales, again likely affected by the Bank Holiday distortion.
"Retailers will hope to recoup that sales deficit in September and to start feeling the effect of higher real wages."
KPMG retail head David McCorquodale said: "September sales will get a shot in the arm from the bank holiday and the comradery of the Rugby World Cup. However, the fashion world will be hoping that last year’s ‘Indian summer’ does not repeat itself, resulting in heavy discounting to move seasonal items."