Marks & Spencer (M&S) is forecast to report its 12th consecutive fall in quarterly sales at its general merchandise division on Tuesday.The UK retailer is expected to blame its transition to a new web platform when it publishes its first quarter sales trading update. The group is likely to post a fall of 1-2% in sales at general merchandise, which includes clothing, footwear and homeware, according to a poll of analysts by Reuters.It compares with a 0.6% decline in the fourth quarter.In May, M&S warned that its new website, which went live in February, would take up to six months to "settle in". The firm assured it was normal in the industry and denied there were problems with the site.The site is part of M&S's transformation into an international retailer to reach customers through stores, the web, tablets and mobile devices.RD