According to the CBI’s latest Distributive Trades Survey, 24 per cent of retailers saw sales volumes rise year-on-year, while 39 per cent reported a fall. That gives a balance of -15 per cent, the weakest since May 2010.
Although sales volume growth was virtually unchanged in August at a fall of 14 per cent, this was slightly weaker than expectations of -seven per cent.
The three-month moving average of sales, which smoothes out volatility in the monthly figures, also declined by 11 per cent, at the fastest rate since August 2009.
Sales were reported to be poor for the time of year by a balance of -30 per cent of retailers, with the decline in volumes felt across almost all the main sub-sectors.
Looking ahead to next month, sales volumes are expected to decline at a similar rate of -14 per cent.
Judith McKenna, chair of the CBI Distributive Trades Panel and ASDA chief operating officer, said: "High Street sales are sluggish but appear to be stabilising.
"However consumer confidence continues to be bruised by a combination of low wage growth, high prices and rising unemployment. Shoppers are still clamping down on discretionary spending and focused on buying the basics at the best price.
"With the consumer squeeze set to get tighter with the winter utility bills rise, we expect retailers will face a challenging October."
The volume of orders placed upon suppliers fell at a balance of -16 per cent of retailers, and is expected to decline at a similar rate next month at -19 per cent.