The CBI said that 37% of retailers surveyed said that sales had risen on a year ago against 25% that said sales were down, giving a balance of +12% - the lowest balance reported this year.
However clothing sales fell back for the fourth consecutive month with a balance of -16% but sales of shoes and leather goods continued to grow, racking up a balance of +49%.
The three month average which reflects the underlying trend in sales volumes, slowed slightly to a balance of +15%.
John Longworth, chairman of the CBI's Distributive Trades Panel and executive director of Asda said: "Retailers will be relieved that the recent troubles on the financial markets didn't have a serious impact on consumer spending in September. However, four consecutive months of more modest spending growth prove that higher interest rates are continuing to have an effect.
"Some retailers are faring worse than others and the return of fierce competition makes pricing critical...The bank needs to keep a watchful eye on consumer confidence, which risks being dented further as a result of increased uncertainty about the economic outlook into 2008."
The September CBI survey was conducted between August 30 and September 19.