The British Retail Consortium, publishing the survey today, highlights the fact this year-on-year pace of growth in retail sales value is the slowest so far this year excluding distortions in the spring related to the timing of Easter.
David McCorquodale, head of accountancy firm and BRC survey sponsor KPMG's UK retail sector practice, said: "These figures are a reality check and will make retailers nervous as we enter the run-up to Christmas."
He added: "The stark fact is the retail recovery remains fragile and, in the lead-up to Christmas, retailers, who are generally carrying less stock than in prior years, will need to manage promotional activity carefully to maintain margins."
BRC director-general Helen Dickinson highlighted the weakness of grocery sales in September.
She said: "While total retail sales have continued to grow this month, it has been the weakest growth so far this year if you exclude Easter distortions."
However, she highlighted the finding that online sales of non-food products such as electricals and leisure goods in the UK in September had been 13.4% higher than in the same month of last year.
Mr McCorquodale said that unseasonably warm weather had stifled sales of autumn and winter clothing collections in September.
He added: "Consumers are still cautious about spending, and are reluctant to restock their wardrobes with winter woollies until the weather cools."