Tablets are beginning to replace desktop computers as shoppers’ preferred device for online purchases, eBay’s mobile boss has said.

Speaking at the Retail Week Ecommerce Summit, eBay’s head of international product Jonathan Gabbai said: “The way tablets are going to go is as a desktop replacement. We need to treat them differently. We have seen a 40% decrease in lapstop purchases and a 400% increase in tablet purchases.

“The launch of Windows 8 is the first step towards desktop and tablet mixing together.”

Gabbai said mobile devices generated £5bn of revenue for eBay last year but it is expecting this to double because of the rise of the tablet among shoppers.

Many retailers are yet to create websites optimised for tablets, having so far focused more on mobile optimised sites and apps.

But competition is fierce among tablet manufacturers in preparation for Christmas, as Apple launched its mini iPad, a smaller version of its hugely popular tablet this week, while Google revealed its new Nexus 7 device this morning and Amazon started selling its Kindle Fire HD tablet just last week.

Brand Alley chief executive Rob Feldman urged retailers to improve the tablet experience for customers in order to increase sales. “Tablets are perfect for retail. The future is huge for tablets. But browsing on a tablet is not necessarily about buying. To get that conversion you need to make sure your site is easy to navigate,” he said.

Schuh head of ecommerce Sean McKee explained it is key retailers offer different services designed specifically for tablet devices and mobile phones rather than offering one mobile site.

“Smartphone customer behaviour is different,” said McKee. “Customers are now more likely to use their mobiles to find out store locations and they are much more likely to be on the go. The tablet is the new desktop.”

McKee said 36% of its online sales were on mobile devices, however he said tablet shoppers convert better to a sale and spend more per transaction compared with mobile phone shoppers.