(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window) * FTSE 100 up 0.2%, FTSE 250 adds 0.2% Aug 20 (Reuters) - London’s FTSE 100 rose on Friday as heavyweight miners recovered from steep falls in the previous session, although a surprise drop in retail sales kept the index on course for its first weekly decline in five. British retail sales unexpectedly fell sharply last month, according to official data. Retail sales volumes dropped by 2.5% in July from June, against expectations of a 0.4% rise. The blue-chip FTSE 100 index rose 0.2% with Rio Tinto, BHP Group, Anglo American and Glencore being among the top boosts. The domestically focussed mid-cap index rose 0.2% with retail stocks leading gains primarily on robust earnings from Marks & Spencer The retailer jumped 10.3% to the top of the mid-cap index after saying it expected its annual profit to be above forecasts. (Reporting by Shashank Nayar in Bengaluru) Our Standards: The Thomson Reuters Trust Principles.