UK online sales rose by just 5% year-on-year last month, making it the weakest August performance since 2000, according to figures from IMRG.
A later bank holiday weekend, which will be included in the September Index this year, was blamed for the overall drop, coupled with a delay in back-to-school shopping.
The IMRG Capgemini e-Retail Sales Index said online sales were down 6% compared to July. Clothing experienced low growth, up 5% compared to 18% in June and 14% in July. The accessories category also had its lowest increase since August 2009, up 14% year-on-year.
Sales made via a mobile device saw an increase of 33% in August.