Online sales climbed 15% year-on-year in September as customers spent £5.5bn.

Ecommerce sales were up 6% month-on-month according to the IMRG-Capgemini e-Retail Sales Index.

Online is continuing to outperform the high-street as, according to the latest British Retail Consortium sales monitor, overall retail like-for-like sales grew just 0.3 per cent on last year.

Despite the rise IMRG and Capgemini have reviewed their original prediction of 18% annual growth for 2011 and downgraded it to 16%. This equates to a 12-14%increase for the fourth quarter which shows that the rate of growth is slowing. In 2010 total growth reached 18%.

Last month clothing, home and garden and clothing performed well, up 40% and 21% year-on-year respectively. Within clothing, online accessories sales soared 43%.

Capgemini head of retail consulting and technology Chris Webster said: “It appears that rather than cutting back entirely, we have been more conscientious in our purchases – faced with uncertainty, shoppers are prepared to cut back on luxuries, but not from shopping altogether. Smaller items, such as clothing and items for the home, are considered rewards for our belt tightening, or just more sensible purchases.”