UPDATE 1-Tesco sales continue to slide -Kantar

LONDON, Oct 21 (Reuters) - Sales at Britain's Tesco , the market leading grocer reeling from an accountancy scandal, continued to slide over the last 12 weeks, although the firm has at least stemmed the rate of decline, industry data showed on Tuesday. The data from market researcher Kantar Worldpanel showed Tesco's sales fell 3.6 percent in the 12 weeks to Oct. 12. Though that performance was still the worst of Britain's so called "big four" grocers, it was Tesco's best figure since Jun