Responding to the Distributive Trades Survey, half of all retailers said that sales volumes in the first half of October were down on the same period last year, with less than a quarter reporting an increase.
The decline matches the figures for September and was in line with retailers' expectations, according to the CBI. No improvement is anticipated in November.
The majority of sub-sectors saw steep declines compared to a year ago, although there were increases in footwear and leather, hardware, china and DIY.
Suppliers have been hit hard too, with 36 per cent of the retailers surveyed reporting a year-on-year fall in the volume of orders placed with suppliers.
Andy Clark, chairman of the CBI Distributive Trades Panel and retail director at Asda, said: "Shoppers face competing pressures on their wallets and are spooked by worries over job losses and the slowing economy."