For the month of September 2013, total retail sales in the UK grew 2.4%, as against 3.4% increase last year and in line with the 12-month moving average.
The rise in sales was mostly fuelled by electricals and leisure goods, while food experienced a decline in like-for-like sales, the agency noted.
Non-food products sales were relatively strong in the UK, which rose 13.4%, against a year earlier. Over the past three months, online contributed a third of the total non-food retail growth.
British Retail Consortium director general Helen Dickinson said the BRC-KPMG data shows that while total retail sales have continued to grow this month, it has been the weakest growth so far this year, excluding Easter distortions.
"Online sales were again the stand out performer, growing by double digits, and contributed strongly to non-food sales such as electricals and leisure items. The launch of our new Online Retail Sales Monitor highlights this, and in fact, without the contribution of online, clothing and footwear sales would have declined in September," Dickinson added.
Grocery sales were hit hard while demand for children’s footwear and clothing increased in September.
KPMG retail head David McCorquodale said these figures are a reality check and will make retailers nervous as they enter the run up to Christmas.
"Unseasonably warm weather stifled sales of autumn and winter collections in September and the recovery in home related items flattened. Consumers are still cautious about spending and are reluctant to restock their wardrobes with winter woollies until the weather cools," McCorquodale added.