(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 0.7%, FTSE 250 adds 0.5% Sept 21 (Reuters) - Heavyweight energy and mining stocks lifted London’s FTSE 100 on Tuesday, with Royal Dutch Shell providing the biggest boost to the blue-chip index after it announced plans to sell its Permian Basin assetsThe blue-chip FTSE 100 gained 0.7% in early trading. Oil major BP and miners BHP Group, Anglo American and Rio Tinto were among the top boosts. Royal Dutch Shell jumped 3.3% after it said it would sell its Permian Basin assets to ConocoPhillips for $9.5 billion in cash, exiting the largest U.S. oilfield as it focuses on its clean energy transition. The domestically focussed mid-cap index rose 0.5%, with travel stocks being among the top gainers. In earnings-driven moves, British home improvement retailer Kingfisher fell 3% to slip to the bottom of the FTSE 100 even as it reported a jump in first-half profit. British transport company Stagecoach Group surged 19.5% after it said it was in talks with rival operator National Express about a possible all-share merger. (Reporting by Shashank Nayar in Bengaluru; Editing by Saumyadeb Chakrabarty)