LONDON, July 8 (Reuters) - British retailer Marks &Spencer's underlying non-food sales fell for a 12thstraight quarter, it said on Tuesday, hurt by the transition toa new web platform.
The firm said sales of non-food products, spanning clothing,footwear and homewares, at stores open over a year fell 1.5percent in the 13 weeks to June 28, its fiscal first quarter.
That compares with analysts' forecast in a range of down 1-2percent and a decline of 0.6 percent in the fourth quarter ofM&S's 2013-14 year.
M&S cautioned in May that its new website, which went livein February, would take up to six months to "settle in". It saidthis was normal for the industry and denied there were problemswith the site.
The firm said M&S.com sales fell 8.1 percent in the firstquarter.
Within the non-food like-for-like figure M&S said clothinglike-for-like sales fell 0.6 percent, having risen 0.6 percentin the fourth quarter.
M&S's food business, which contributes over half of groupsales but less profit, is performing much better, delivering a19th consecutive quarter of growth.
Its sales on the same basis rose 1.7 percent, versusanalysts' forecasts of up 1.5-2.5 percent and a fourth quarterrise of 0.1 percent.
M&S said its full year guidance remained unchanged. (Reporting by James Davey; editing by Kate Holton)