Topshop is to launch an app and mobile optimised site in the coming months as mobile becomes an increasingly important channel for retailers.

It is understood mobile sales at Topshop account for 8% of all online sales with mobile sales growing by three to four times over the last year.

The Arcadia-owned high street retailer is seeing a higher proportion of sales coming via mobile phones than the average for retailers despite the fact it is yet to launch a mobile-optimised site. Online retail group IMRG said that its members have an average 3-4% of total ecommerce sales coming from mobiles compared to Topshop’s 8%.

Kate Walmsley, head of ecommerce at Topshop, said that including sales via iPad 8% of e-commerce sales are now coming via mobiles and added that Topshop believes it to be a very important channel.

In the last three months Topshop launched a marketing initiative with mobile gaming service SVNGR aimed at students which rewarded challenge completions with free gifts, discounts and competitions.

Other retailers have predicted a rise in sales from mobile phones with many launching mobile optimised sites and apps to capitalise on the sales. New Look launched iPhone and iPad apps last month and in September department store group Debenhams launched a mobile-enabled site.

eBay said it expects mobile commerce to generate almost $5bn (£3.1bn) in merchandise volume this year and Paypal mobile to exceed $3.5bn (£2.2bn) in payment volume.