E-commerce retail sales reached a new all-time high in May as the sector's growth accelerated to its fastest rate of increase in eight months, new research has revealed.

According to the latest index from Interactive Media in Retail Group (IMRG), online shopping growth outstripped the high street by a factor of 40 in May, despite widespread aggressive discounting by bricks and mortar retailers.

UK shoppers spent over £1.5bn online during the month, 35.6 per cent more than a year earlier and 13 per cent more than in April.

In stark contrast, total retail sales growth was at its slowest rate since 1947, according to the latest government statistics, with a year-on-year increase of just 0.9 per cent.

"In a tough retail environment, large numbers of consumers are opting for the convenience and value that they are now confident of finding online," said Jo Tucker, managing director at IMRG.

"And the internet is a great trading medium for retailers too: it gives them real-time feedback on consumers' buying moods, enabling them to continually optimise with great precision their offers, ranges, prices and stock levels in order to maximise profitability."

IMRG chief executive James Roper added that many factors are contributing to the growth of online shopping, including the rapid take-up of broadband, more secure payment mechanisms and improved delivery options.

"However, no component is more important than the online shopping services themselves, and these are getting much better," he said.

"The customer journey is becoming easier, product ranges are wider, merchants are using clearer images and richer product information, and linked selling features add value by drawing attention to relevant accessories, options and associated products."

IMRG noted that, while there are strong online merchants in many sectors, there are still large gaps in the online market, such as high-end fashion, indicating that scope exists for further industry growth.