Online sales growth is weakening, with August seeing a large drop in year-on-year growth compared to previous months.
Internet retail sales are still growing faster than the high street with a year-on-year growth rate of 7.9% in August, compared to a 0.1% high street decline. But the rate of growth has slowed dramatically from December last year, which saw growth of 30%.
The figures also show a drop from July this year, when online sales grew 20%.
The British Retail Consortium, which released the figures, said sales in June and July were boosted by good weather and clearance sales, but they dropped in August when these ended.
Sharon Hardiman, head of non-store retailing, said: "This is the second-weakest growth we've recorded in the 11 months this measure has been running, and well down on July's figure. Customers are pulling back and it's clear the stronger sales of previous months were driven by seasonal factors and promotions - not any widespread return of consumer confidence."
The British Retail Consortium noted that while online sales continue to outperform store sales, the expansion is from a very low base - internet sales still only account for about 4% of total retail sales.